(idiomatic) To consider or regard; to include (as in an estimate or plan) or pay attention to; to notice; to allow for. His plan did not take into account the possibility of rain.

What does it mean by taking into account?

If you take something into account, or take account of something, you consider it when you are thinking about a situation or deciding what to do.

Is taking into account correct?

Well, yes, by taking into account is fine.