We use CAN to show that someone has the ability to do something now.
I can play the piano.
Can you speak English?
They can’t play football very well.
We use COULD to show that someone had the ability to do something in the past.
I could play the piano when I was a child.
Could you speak English when you were a teenager?
They couldn’t play football very well last year.
We use WILL BE ABLE TO to show that someone will have the ability to do something in the future.
I will be able to play the piano when I finish this course.
Will you be able to speak English when you move to the USA?
They won’t be able to play football if they don’t practice.
