Meaning of “sum sth/sb up” - Learner’s Dictionary

sum sth/sb up

phrasal verb with sum uk us /sʌm/ verb (present participle summing, past tense and past participle summed)

to quickly decide what you think about something or someone:

I think she summed up the situation very quickly.

(Definition of “sum sth/sb up phrasal verb, verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)