Meaning of “firsthand” - Learner’s Dictionary

firsthand

adjective, adverb uk us /ˌfɜːstˈhænd/

experienced, seen, or learnt directly:

Police heard firsthand accounts of the accident from witnesses.
The soldiers knew firsthand about the horrors of war.
firsthand experience

(Definition of “firsthand” from the Cambridge Learner’s Dictionary © Cambridge University Press)