折寿 means 'to shorten one's life' — usually used as a self-deprecating remark when someone receives excessive kindness or hospitality, implying that the favor is so great it might reduce the speaker's lifespan. It's a separable verb (离合词): the object 寿 can split off from 折 when inserting a measure word or complement, as in 折了寿. The word carries a cultural sense of modesty and superstition — you might say it when someone goes out of their way for you, or when you feel you don't deserve the treatment.