What does cf mean before a verse of scripture?

Oh, dude, "cf" stands for "confer," which is just a fancy way of saying "compare." So, when you see "cf" before a verse of scripture, it's like a little nudge saying, "Hey, maybe check out this other verse too, if you feel like it." It's just a casual way of saying, "Hey, this verse might be related to that one, or it might not, who knows, like, whatever."