Not everything about Croatian is complicated: Although the language does differentiate between masculine, feminine and neuter nouns, it's generally very easy to figure out which words are which.
Grammatical gender is a specific form of noun-class system. Simply put, it means that every noun in Croatian is either masculine, feminine or neuter.
It's easy to do it for nouns that denote living things – if a person or an animal is male, its grammatical gender will be masculine, and for living things that are female, the grammatical gender will be feminine.
What makes it slightly more complicated is that the names of inanimate objects also have a gender, which is not determined by any of the characteristics of the object.
Rules in Croatian as regards noun gender are fairly straightforward and the gender is determined based on the last letter of the word:
Masculine (muški rod)
Words ending in a consonant are masculine
(except about 250 nouns which are feminine but have a special declination)
Examples: muž (husband), susjed (neighbour), stol (table), ručak (lunch)
Feminine (ženski rod)
Words ending in -a are feminine
(except a very small number that are masculine)
Examples: voda (water), mama (mother), stolica (chair), čaša (drinking glass)
Neuter (srednji rod)
Words ending in -o or -e are neuter
Examples: more (sea), kazalište (theater), kino (cinema), pivo (beer)
sunce – sun Answer neuter (srednji rod)
računalo – computer Answer neuter (srednji rod)
večera – dinner Answer feminine (ženski rod)
jezero – lake Answer neuter (srednji rod)
doručak – breakfast Answer masculine (muški rod)
kuhinja – kitchen Answer feminine (ženski rod)
prijatelj – male friend Answer masculine (muški rod)
prijateljica – female friend Answer feminine (ženski rod)
miš – mouse Answer masculine (muški rod)