Learn Polish: Kobieta je smaczną sałatkę. - The woman is eating a tasty salad.

In this sentence, the tasty salad is the direct object—the thing being eaten. In Polish, direct objects take the accusative case. For feminine singular words, a noun ending in -a (like sałatka) changes its ending to -ę (sałatkę), and an adjective ending in -a (like smaczna) changes its ending to -ą (smaczną).

Is there an easy way to remember which word gets -ą and which gets -ę?

Yes! A great rule of thumb for the feminine accusative case is that adjectives take the letter with the "tail" facing right (-ą), like smaczną, while nouns take the letter with the "tail" facing left (-ę), like sałatkę. Learners often mix these up, so remember: adjectives get -ą, nouns get -ę.

Since kobieta (woman) is also a feminine noun, why doesn't it change its ending too?

Because the woman is the one doing the eating (she is the subject), so kobieta stays in its basic, dictionary form (the nominative case). Only the receiver of the action (the salad) changes to the accusative case.

The translation says "is eating", but couldn't je also mean just "eats"?