I had a problem with my girlfriend and just sent me a text message saying; Let's calm down. What do you mean?

There is always constant friction between two people, so as to better understand each other. It's normal to have contradictions. Calm down is a good thing. Why are you fighting? Where is the root cause? Don't worry, in the process of calming down, you should also think about what your problem is. This won't make the problem worse!