Latin is the language which the ancient Romans used to speak.
ADJ
（国家）操拉丁系语言的；拉丁语系国家的
Latin countries are countries where Spanish, or perhaps Portuguese, Italian, or French, is spoken. You can also use Latin to refer to things and people that come from these countries.
Latins are people who come from countries where Spanish, or perhaps Portuguese, Italian, or French, are spoken or whose families come from one of these countries.