Exercising for badminton is done to become a better player. (And maybe for other reasons, like condition and health.)
All aspects of the badminton game can be trained by exercising.

Sometimes exercising is seen broadly. Also playing matches are then seen as exercising.
-Just by playing matches will playing badminton become better. So, learning by doing. Thereby evaluating the own play will facilitate learning.
-It's possible to plan an aspect of the game into a match. Before starting to play, an idea is borne in mind and that will be tried to perform. That might be to concentrate, to place well, to more spontaneously playing, to give attention to grip or a stroke, etcetera.

Mostly, exercising is comprihended as training of a part of a game of any kind. Then repeating is the way of learning that part, or of building that up.
The conditions for playing badminton can all be trained by exercises.
-Physical condition, like power, stamina, coordination, flexibility, speed, reaction.
-Mental condition, like rest, attention, open mind, fantasy, thoughts, reacting.
-Techniques, like strokes, moving, integration of these.
-Tactics, like placing, defending, positioning, these for singles, doubles and mixes.
Trained parts are integrated into the game. It's convenient to take that into account when exercising and playing.

Exercising can be done too when looking at matches. That's a mental training. By empathetically and actively trying to understand playing, aspects can be learned and trained. These are such as attitude, tactics, and techniques. That can be done from the internet too.