I've started to learn Marathi language.

I've started to learn Marathi language.

Today, I learned vowels.

अ [a] आ [ā] इ [i] ई [ī] उ [u] ऊ [ū] ए [ē] ऐ [ai] ओ [ō] औ [au]

I don't understand ऋ.Is this a vowel?

Yes . ऋ  It is pronounced a 'r' with a rolling tongue.

It is difficult for me to say the pronunciation in written form because I dont know phoenetics.