Translating game files

I'd like to create a translation mod to have my game displayed in a language it does not currently support.

Does anyone know how to start with it? When I try to look it up, the results usually are about translating mods.

I think it should be possible, since I remember seeing one YouTuber tweak some in-game names so they sound better in the language they used for the game.

Thank you everyone in advance 😄