Obvs is a jokey, spoken-and-text shortening of obviously. People add a little -s on the end the same way they make totes from totally or blates from blatantly — a cute, insider cut-down, not a grammar rule. It means “of course,” “that’s clear,” and it often carries a shrug: well, duh. Young people, especially in British informal English and on the internet, use it in messages and casual talk. It can be friendly, and it can sting a little, as if the other person should already have seen the point. It has no place in school essays, emails to teachers, or anything that needs to sound careful. Though actually, even among friends it can hurt if you use it when someone honestly did not know — it says the answer was too obvious to bother explaining.