They are like acheivements in a video game or suchlike.
If you click on the number of points you have, it should say why you got them, and there should be another link to show everything available... Like number of posts, or likes or whatever else. I am using the mobile software, and I cannot see a way to show you directly unfortunately.
And I think the message limit for being able to send personal messages is something like maybe 5 or so... I cannot remember.
Maybe a staff member will chime in with suitable links.