This is the 3017th most frequent Catalan word.
interessats
"Interessats" means "interested people" or "those who are interested" in English.
Here, 'interessats' is used as a noun referring to people who are interested.
Els interessats en el curs poden registrar-se abans de dilluns.
Those interested in the course can register before Monday.
In this case, 'interessades' acts as an adjective, modifying 'persones' and agreeing in gender and number.
Estem buscant persones interessades en unir-se al voluntariat.
We are looking for people interested in joining the volunteering.
'Interessats' here functions as a noun referring to individuals interested in classical music.