We use the present continuous to talk about a specific action that is occurring.
The specific action is not finished.

(ex)  He was hitted by a car when he was cycling home yesterday.
(ex) She is taking a shower.

We use the present continuous to talk about a general activity that takes place
over a period of time. ( a period around now)

(ex) Are you studying hard today? Yes, I think today topic is very difficult.
(ex) Are you enjoying a soccer game? Yes, it is very interesting.

We use the present continuous to talk about future arrangement.

(ex) What are you doing tomorrow? I am decorating my room.
(ex) I am going to have a dinner with my friend tomorrow.

When we describe present situation, we use the present continuous.

(ex) Asian economic situation is already bad and it is getting worse.
(ex) She wants to study in Australia, so she is learning English