Is the expression "be clear" used often? What does it mean in here?

Native speaker’s answer
Rebecca
Yes, the word "clear" as used in this context is used quite often. In this context, to be "clear" about something means to be very direct or specific about something or to give very detailed instruction or explanation. Ex: They were clear that if we trespass, they will call the cops. Ex: She made it pretty clear that she doesn't like me.