Meanings
Usage patterns
〈物〉に符を打つto put a mark/seal on something
He marked the important section.
符を計算するto calculate the fu (mahjong score)
He calculates the fu for his hand.
符を身につけるto carry a charm on one's person
He carries a charm to ward off bad luck.
Expressions
疑問符が付くthe question remains; it comes into question