What you wear to a samba class. Again, you want to make sure what type of samba class you are going to. If this is an intense cardio workout-based samba class, you want to make sure you're wearing breathable fabric, because you're going to be sweating, you're going to be dancing and jumping through the whole time. Most of all, you want to make sure you have a comfortable range of motion, which means you want to make sure you're comfortable if you roll on the floor, to have a seat on the floor if you need to do the kneeling position. You want to make sure that your knees are also covered, and you want to make sure that you are able to have long arms and legs while you're doing your samba routine.
For an example, if you're doing an Afro-Brazilian samba class, it's an hour and a half of intense dancing. You're going to be dancing through the whole time. In the Afro-Brazilian class, we do dance at (?), you might be going onto the floor. For that, you want to be prepared. Make sure that you have support for your knees and make sure that you have a good range of motion to go onto the floor.
If you were taking a social samba dance class, which means that it's more towards the ballroom side, and you were going to go after work, then you might be wearing your workout wear. However, you want to make sure that you do have range of motion, so be careful with really tight pants and tight tops that are going to prevent you from moving the torso. It's going to prevent you from moving your hips. It's also preventing you from lifting your knee up to hip height. You want to make sure that you are wearing a nice, comfortable outfit, but also accommodating between comfortable and looking cute, of course.