Rehabilitation exercise is a type of exercise that restores your health, flexibility, and strength. There are often used after an injury or health.
Let's look at this way:
You broke your leg and can't walk for about 3 months.
After that 3 months, you try to walk, but you can't
This is because you hadn't been using your muscles, so you're weak.
To regain your stregnth, you do these special exercises.
These special exercises are called rehanilition exercise.
Hope this helps. If you have any questions, please put them in the comments below.