English grammar

"to do so" may mean ability to do something.

It refers back to the meaning in the sentence. You should have given us a sample sentence to be sure.

Here's an example;

He can work 12 hours and has the time to do so this weekend.

And if Punkey's explanation does not cut it, you should give the phrase in context.

Yeah.

Your room is in a mess. Go and tidy it up, and I expect you to do so every day in future without being told.