I suppose you were asking about the Present Continuous. You can use this tense when talking about an action that is still in progress. I play tennis every week. (Present Simple - referring to a repeated action) - I'm playing tennis now. (Present Continuous - referring to an action which is still in progress) It usually rains a lot in the spring. (Present Simple - refers to a fact that is true in general) - It's raining. (Present Continuous - what is happening now) Hope this helps.

You use it most often for activities happening now or around now e.g. I am writing some words now He is reading a book this week