What does it mean when a girl likes a guys photo?

[Gavin Workshiers]

Okay,

I have an old friend that I hate now because of personal reasons. He is quiet hot , considered by girls. He gets lots of likes on instagram (around 40-50).
There is a girl in my year that I have a crush on, and she recently liked his instagram photo of himself. They never talk in school but they use to be friends in middle school but haven't talked since. What does it mean? Does it mean my crush has a crush on him? He has the worst personality and I can't stand her liking his pictures.
And also he post hashtags such as: "#l4l" and "#likeforlike" so does that mean they are just trying to get likes and nothing else?
But there was one when he didn't post "l4l" and she still liked it. What does It mean and why? Thanks!

[Adam]

It means she likes the photo? Jesus, stop overthinking things

[Corina]

wow... uh you sound creepy!!!!!!!
it means nothing ...

[Lucy]

It means she like the photo jeezo I though I over thought.