something a girl will say in the middle of sentences with a little squint and head cock to register that you agree with her, but without waiting to see if you actually do (know what she means, or agree) before continuing on with what she was talking about.
Can be abbreviated to you know if she is in a hurry to get to a lot of important information.
further abbreviation while texting is commonly seen as u no? this version eliminates entirely the need or possibility for instant approval (real or imagined), requiring the textee to actually respond, or risk insulting her by not automatically taking her side.