Meaning of “see through sb/sth” - Learner’s Dictionary

see through sb/sth

phrasal verb with see us uk /siː/ verb present participle seeing, past tense saw, past participle seen

B2 to understand that someone is trying to deceive you:

I saw through him at once.

(Definition of “see through sb/sth” from the Cambridge Learner’s Dictionary © Cambridge University Press)