What does it mean when a guy sends you a picture of himself?

[Cutie Pie]

So there's this guy in my class and that is where we met. He asked me for my twitter and instagram. A week later he gives me his phone number but doesn't ask for mine. He's always joking around with me and asking me how a certain event went if I told him I was going to to do something over the weekend. Yesterday we walked with each other to go to each of our cars. I texted him asking about a paper a professor asked us to write he have me an answer then sent me a picture ( he was fully clothed) and said "Something to brighten your night ". Why do you guys think he sent me the picture and what do you think about him, given the little info I have given him.
P.S. He lives like 2 min. away from my house and he has a nickname for me. He's always staring at me too but in a way in which he doesn't want me to see that he is staring at me.