Can someone please explain: why "hodl"? Why not "hold"? Does hodl mean hold or what?

3 months ago I thought it was too late... Now I think 3 months ago was perfect and now is too late... What do you think, friends? When will it be too late?

Hi guys! I posted 2 comments today and now have Activity=2. I can't get how it works, I created my account this morning, and the activity should be updated every 2 weeks... or not? Please help me!