Surfing conditions in Dakar range from pretty good to heart-thumpingly good.

If you’re learning from scratch, there are plenty of schools/instructors, a couple of forgiving beach breaks to practice in whitewater (green waves), and a couple reef breaks suitable for beginners if you want to get onto an open face sooner.
Malika Surf Camp, Ngor Island Surf Camp and SeneSurf-Virage all offer beginner lessons. So does Secret Spot, Surfer's Paradise and Quiksilver.
Urchins cover the sea floor at all reef breaks, so either booties or a stout the-floor-is-lava mentality are necessary defense mechanisms. Even with both of these, though, you will get urchined, (and it it's not so bad once you're used to it and become good at digging out the spines).
If you already know what you are doing, you are going to love it here. The peninsula of Almadies juts out into exposed Atlantic providing an enormous swell window that allows for waves coming out of the south, west, and north. The waves are all fairly easy to access and most are within very short striking distance of many faculty homes.
South Coast: Ouakam, Secret Spot, Vivier & Club Med
The south coast--where I surf on a daily basis when conditions allow (walking distance from my house)--is peppered with reef breaks that light up on a regular basis; they receive swell straight from the south in summer and refracted swell out of the north and northwest in the winter). While there are still options for beginners in the winter, winter is also when things get really exciting for the better surfer. You will need a wetsuit (and a lot of heart, sometimes), but when big swells come in, they bend around the peninsula and stir up waves that any surfer in the world would kill to be on. Oukam is the best example of this. The reef at Oukam, one of the most picturesque spots in Dakar, provides a right and a left, both of which are hollow, powerful, sometimes hair-raising rides. This wave only really fires a handful of times a year, so make sure you are on it when it does.

Off of the beach road in Almadies (where many faculty apartments are) is where I surfed the most. 'Secret', a wave that is not a secret at all, is your best bet as a beginner. It is often crowded, however, and the wave quality is not top-notch, though it does have its days. Just down the coast are two waves--Vivier Right and Left. These waves are a blast to surf. The right is short, but punchy, providing little barrels if you can manage to sneak into them and a couple of nice sections to practice tightening up your turns. The left I don't know as well, but it is a body-boarder favorite, meaning quick and steep. For the goofy-footer, the left seems like very good time. The right you can surf at any tide (best at lower-mid tides, usually), but the left is only surfable at higher tides because of the reef that breaches when the water is drawn out.
In the distance from both Secret spot and Vivier, you will some times see beautiful waves feathering against the sky. This is Club Med--named after a long gone Club Med that used to face it. Now it breaks in an isolated part of the peninsula where a new hotel is under construction, giving you a nice escape from surfing in front of bars and restaurants. On small days, this wave can still provide some very fun rides. It is longer than the others on the south coast, and a lot more powerful. On days when it pumps, it is beautiful and humbling (never been so beat up by a wave as I have by this one). Surf with someone here, as you are further away from help if you need it and that potential that you may need it is higher.
North Coast: Ngor
Peeling off both sides of the island of Ngor, which is north-facing, are two fun waves--Ngor right and Ngor left. The right is the iconic 'Endless Summer' wave that the surfers first find on their stop in Dakar. It almost always receives surfable swell, making surfing there only a question of wind (and tide timing, as low tide is pretty sketchy). All winter, the winds are pretty relentless out of the north--onshore and choppy--making it often unsurfable. Little windows of calm appear, though, and you can jump on it when they do. You can still keep your eye on the forecast for these north swells, though, because if they are big enough, all that energy will wrap around and activate the above mentioned south coast spots (the more west there is in the swell direction, the better for this effect). The relentless north winds mean that the south coast is literally off shore every day: if there is swell hitting the south coast, the wind in the winter is always favorable.
There are many more spots than the ones I've mentioned here: Yoff and Virage are great beach breaks for beginners. There are spots south of Dakar and north of Dakar and even spots in Dakar to explore.
There are also a lot of little details that you'll pick up quickly (where to get in, where works best when, etc.) As a newcomer arriving in the summer months, head over to Secret spot and Vivier to meet the surfers and check out the easily accessible waves. The community of surfers here is fairly unaggressive compared to many parts of the surfing world, so you're coming at a good time.
The World Surf League (WSL) had their first event here this year, though, so this may all change soon. The Senegalese surfers are welcoming and kind and more than happy to help get you oriented. If you are not a surfer at all, I encourage you to become one here. It is extremely rare to find so many waves with so few people on them right in a capital city.
I have loved getting to know the ocean and the waves here. If you want more specific information, don't hesitate to contact me: johannesn@faculty.isd.sn