so when you want to say "I am studying" you can say "나는 공부하고 있어요" you just need to put "~하고 있어요" after object!

ooow korean also have a grammar (-_-)??

I will tell you some examples. If you eat apple, you can say like this. 나는 사과를 먹습니다. (I eat apple.) - present tense But you want to express it as "~ing" 나는 사과를 먹고 있습니다. (I'm eating apple.) - present progressive