Answer:
metaphor
Step-by-step explanation:
metaphors are figures of speech that compare two unrelated things by stating that one thing is another. In this case, the metaphor compares the idea of having hidden knowledge to the act of hiding tricks up one's sleeves.
in this sentence, the phrase "tricks up your sleeve" is used to convey the idea of having secret or hidden knowledge or skills that can be used to your advantage in a particular situation.
it is not meant to be taken literally, as it is comparing the idea of having hidden knowledge to someone hiding tricks up their sleeves.