Calling a spade a spade means that you give your direct opinions or thoughts about something. If you don’t like something or you disagree, you say it. If you do like something, you say good or positive things about it. When you call a spade a spade you are not shy about giving your true opinions.
Example:
I do not think that this plan is going to work. I’m going to have to call a spade a spade.