The locative case is used (mainly) to describe where something is.
Perhaps it's most important use is with the preposition u with the meaning 'in' a location. So learn this one!
The singular ending for the locative differs according to the noun gender.
The locative plural is the same for all genders and is im for adjectives and ima for nouns.
u filmovima 'in films'
u restoranima 'in restaurants'
u kojima 'in which'.
Zbog pandemije naši državljani sve više napuštaju strane zemlje u kojima su živeli '... in which they lived'.