The Ukrainian language has a vocative case (кли́чний відмі́нок) that is used to address or call someone directly. It is used when you want to get someone's attention, address them in conversation, or call out to them. Word "кли́чний" comes from the verb ‘кли́кати’ (to call).

Приві́т, Іва́не! - Hi, Ivan!

The vocative case can be used with inanimate objects too.
Зе́мле моя́! - My land!

What ending to use?

Endings, suffixes or other rules	nominal case	+ ending	vocative case
ends in a consonant	Брат (brother) студе́нт (student) друг (friend)	-е	Бра́те студе́нте дру́же*
Suffix: -к-, -ик-, -ок-, -ко-	батько (father) + some family members: та́то (dad) ді́до (grandfather) син (son)	-у	батьку + some family members: та́ту ді́ду си́ну
ends in "-ь / -й / -ар"	Діду́сь (grandfather) Андрі́й (Andrew) лі́кар (doctor) Хло́пець	-ю	Діду́сю Андрі́ю лі́карю
ends in "-а"	Ма́ма (mom) дочка́ (daughter) кни́га (book)	-о	Ма́мо до́чко кни́го
Personal names and some diminutives	Ната́ля (Natalya) бабу́ся (grandmother)	-ю	Ната́лю бабу́сю
ends in "-ія"	Ната́лія (Natalia)	-іє	Ната́ліє
ends in "-я"	земля́ (land, earth, ground) во́ля (freedom)	-е	зе́мле во́ле
[ neuter nouns ]	мо́ре (sea) вікно́ (window)	-	same as nominal case
[ plural nouns ]	хло́пці (boys) брати́ (brothers)	-	same as nominal case

It is important to note that the Vocative case is not used as frequently in Ukrainian as some of the other cases, but it is still an important aspect of the language for addressing people directly.