A 'case' is a grammatical category which refers to the different forms certain words take depending on their function in the sentence.
In Croatian, nouns, adjectives, pronouns and numbers are always declined, which means that they change slightly depending on the case that they're in.
Modern English has largely lost its case system, however case distinctions can still be seen with personal pronouns:
“Ovo je moja sestra” – This is my sister
(nominative, sestra is the subject)
“Znaš li moju sestru?” – Do you know my sister?
(accusative, sestra is the object)
“Dao sam poklon sestri” – I gave a gift to my sister
(dative, sestra is the indirect object)
“Idem u kino sa sestrom” – I’m going to the cinema with my sister
(instrumental, doing something with someone)
Although there’s no easy way to learn the endings apart from learn them by heart, there is some good news:
Although students eventually learn all of the cases, in terms of being able to communicate not all of them are equally important in Croatian, simply because some of them are used much more often than others.
Also, it might make you feel better to know that Tsez, a Northeast Caucasian language spoken in parts of Dagestan, is considered to have 128 cases, 64 for the singular and 64 for the plural!
Students planning to learn Croatian only have to learn seven cases.