This is the 12390th most frequent Polish word.
muzealnikiem
A "muzealnikiem" is a museum worker or specialist.
The word 'muzealnikiem' here is used as the instrumental case of the noun 'muzealnik', meaning museum professional, indicating a person's role or aspiration.
Zawsze chciałem zostać muzealnikiem, aby pracować wśród zabytków.
I always wanted to become a museum professional to work among historical monuments.
In this sentence, 'muzealnikiem' is used in the instrumental case describing the occupation of the subject, 'friend'.
Mój przyjaciel jest muzealnikiem i oprowadza grupy po wystawach.
My friend is a museum professional and gives tours of exhibitions.
Here, 'muzealnikiem' identifies the person being spoken about, emphasizing their expertise tied to museums.