Learn Polish: W pasiece trzeba stać spokojnie wbrew własnemu instynktowi. - In the apiary, you must stand calmly contrary to your own instinct.

The preposition wbrew means "contrary to" or "against," and it always requires the Dative case. Because instynkt (instinct) is a masculine noun, it takes the typical Dative ending -owi, becoming instynktowi. The adjective własny (own) agrees with it by taking the masculine Dative ending -emu, giving us własnemu instynktowi.

Is there a difference between wbrew and przeciwko? Could I use przeciwko here?

You could technically use przeciwko since it also means "against" and takes the Dative case. However, wbrew specifically emphasizes doing something "in spite of" or "contrary to" a rule, expectation, or nature (like an instinct). Przeciwko is usually more active or confrontational, like fighting or voting "against" an opponent.

Why is the word for "apiary" spelled pasiece here?

The base word is pasieka, a feminine noun. The preposition w (in) describing a location triggers the Locative case. For feminine nouns ending in -ka, the Locative ending causes the consonant k to mutate into c before adding the -e ending. Therefore, pasieka changes to pasiece.

Why does the sentence use the impersonal instead of just saying (you must)?