sikhti hoon aur sikh rahi hoon?
Main hindi sikhti hoon.
Main hindi sikh rahi hoon.

Wich is correct in that case, if i want to tell that i learn hindi, because i want to know it.

Question

sikhti hoon aur sikh rahi hoon?
Main hindi sikhti hoon. 
Main hindi sikh rahi hoon.

Wich is correct in that case, if i want to tell that i learn hindi, because i want to know it.

Answer

Both actually :)

Main hindi sikhti hoon. - I learn Hindi -  Simple Present Tense
Main hindi sikh rahi hoon. -I am learning Hind - Present Continuous