It simply means....
1) 무슨 말/뜻 입니까?(mu seun mar tteus ip ni kka) - formal and polite
2) 무슨 말/뜻 이죠?(mu seun mar tteus i jyo) - informal and polite
3) 무슨 말/뜻 이야?(mu seun mar tteus i ya) - informal and impolite
Here "말","뜻" and "의미" are interchaneagle.^^
^________^