Gender, number, and case.
You may have come across those in German, for example -- ein guter Mann, eine gute Frau, ein gutes Kind (a good man, a good woman, a good child), where the adjective changes according to the grammatical gender of the noun -- and in the accusative, it would be einen guten Mann with yet another ending because it's a different case.
Similarly in Czech: dobrý would be masculine nominative singular, dobrou feminine accusative singular.
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