for example when you're talking to someone and he says something weird, you will say 'this doesn't make sense' it means, it's not logical. :)

This is not a "mean" word. Maybe you are saying that you know the "meaning", or know what it means. "To make sense" - this is an idiom that means something is logical, sensible, and the right thing to do. You could say, "That makes sense, to close the door every time you go outside or come in, so the flies and mosquitoes don't come in the house. I think I should remember that!" "That only makes sense, to put the milk in the refrigerator so it doesn't get sour, so why don't you do it every time you take it out of the fridge?"

make sense 1. To be coherent or intelligible: "an explanation that made sense." 2. To be practical or advisable: "It makes sense to go now." "This passage doesn't make (any) sense." (= the meaning is not clear). "I've read the letter twice, but I can't make (any) sense of it." (= I can't understand it).