"+/-REP" short for reputation
/ˌrepjuˈteɪʃn/

​the opinion that people have about what somebody/something is like, based on what has happened in the past.
E.g.
"+rep good player"
"+rep I am rather thrilled to encounter suchlike quality thy has enlightened us with"
"-rep ♥♥♥♥ ♥♥♥♥♥ долбоёб"
"-rep still gold ranking after all this hours noob! plz cri me a riverrXDDDD"
"-rep
📂Documents
└📁Counter-Strike: Global Offensive
 └📁Skill
 └⚠️ This folder is empty"
"+rep Dear winner
Your SteamID is selected as winner of Weekly giveaway.
Get your ★ Butterfly Knife | Doppler Phase 2 on {insert link here}
Use personal code:
YR56ikLMv5u7"

well this is all cleared out and i have decided to give you a:
+rep nice player