This is the 3782nd most frequent Polish word.
największe
"Największe" means "the biggest" or "the greatest" in English.
In this sentence, 'największe' is used as an adjective in its masculine form 'największym,' describing the noun 'miastem' (city).
Warszawa jest największym miastem w Polsce.
Warsaw is the largest city in Poland.
Here, 'największe' directly modifies the noun 'jezioro' (lake) in its neutral form as an adjective.
Największe jezioro w Polsce to Śniardwy.
The largest lake in Poland is Śniardwy.
In this sentence, 'największej' is the feminine form and is used as an adjective describing 'pomocy' (help).