Downtown refers to the area beyond the three-point line on the court. When a player shoots from downtown, they are attempting a long-range shot. Making a basket from downtown is worth three points instead of the usual two.
The downtown area is far from the basket, so shots are more difficult. Players need strong shooting skills and range to consistently score from downtown. However, making downtown shots can give their team a big scoring boost. Technically, shots made from this area are often very impressive.
Commentators often use the phrase "from downtown!" to describe a long three-point shot. Hearing a player is "heating up from downtown" means they're making several impressive long-range baskets. Downtown shooting can be a game-changer by forcing the defense to spread out more.
Eg. Stephen Curry shot a 3 from downtown.