People can tell if a tree is good or bad, and what type of tree it is, by the fruit it produces. Jesus uses this as an unexplained metaphor—we know what kind of person someone is when we see his actions. (See: [[rc://en/ta/man/translate/figs-metaphor]])
People recognize the kind of tree by the fruit it bears. This can be stated in active form. AT: "people know the type of a tree" or "people recognize a tree" (See: [[rc://en/ta/man/translate/figs-activepassive]])