Meaning of “declare” - Learner’s Dictionary

declare

verb [ T ] uk us /dɪˈkleər/
SAY PUBLICLY

B2 to announce something publicly or officially:

to declare war
[ + that ] Scientists have declared that this meat is safe to eat.
TAX

B1 to officially tell someone the value of goods you have bought, or the amount of money you have earned because you might have to pay tax:

Do you have anything to declare?

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