Spanish-Mexican slang which means to "calm down".
In proper Spanish grammar, it literally means "calm her down". But it can be used to mean to calm anything down.
Say there is an argument, but one person is calm while the other is talking loud. The calm person will say "Calmela!".
A calmservative is basically a play on the word conservative. Popularized by youtuber MaximillianMus, it basically means you win all your arguments by being calm.