A "wink" is a quick way for a member to let you know he thinks you're hot - or wants to talk to you. You can send a "wink" by clicking on the "wink" button on the profile of the member you want to send it too. He will receive an email letting him know that you have winked at him.
If you have received a "wink" from another member, you can respond directly to his email, just like any other.
If you would like to remove the ability to receive winks from other members, simply go to Account > Basics > Uncheck the box next to "Allow other members to send me winks" and click the save button in the bottom right hand