An example is if your trying to state something and you're not sure if the other person will understand what your talking about and has had similar experiences "I could just ride the bus for hours and see where it takes me, you know what I mean?"

it can be a 'filler' in a conversation, like saying 'you know' at the end of a sentence. especially by young Londoners, who say it rapidly and pronounce as 'na wa a meen?' but of course you can also use it, again at the end of a sentence, if you want to check whether someone is understanding you or agrees with you