Wink is a facial expression made by briefly closing one eye. A wink is an informal mode of communication usually signaling, depending on context, sexual attraction or shared hidden knowledge or intent.

Sexual/Flirting: In some cultures it is usually a sexual interest, or flirtatious manner, during momentary eye contact. This is often followed by a smile, and usually a smile from the receiver, if it is accepted/approved, or combined with blushing if they are embarrassed.

A smile from the receiver (usually a woman) indicates her (sexual) interest in the man who winked at her.