It's 몰라 [mol-la].
When ㄹ is in the end of a syllable, it sounds like "L".
curry - 카레 - [ka-re]
foot - 발 - [bal]
water - 물 - [mul]
Water is clean. - 물이 깨끗해. [mu-ri]
in the water - 물 속에 [mul so-ge], 물 안에 [mu-ra-ne]
Did you notice the difference? When ㄹ is followed by a vowel(이, 아, 오, 유, etc. : these are just one vowel without ㅇsound), it sounds like R-ish ㄹ. :-)
You know what, there's even a pun about this '몰라'.
Q : 너 '어금니'를 영어로 뭐라고 하는지 알아? (Do you know how they say '어금니' in English?)
A : 몰라. (I don't know.)
Q : 맞았어! 어떻게 알았지? ㅋㅋㅋ (That's correct! How did you know that? lol)
The pronunciation of 'molar' is different from 몰라[mol-la]. But they sound similar to Koreans. (In some province, they sound a lot similar. -0-) ㅋㅋ Did you get this joke? :-)