I don't understand how translation works in Wordpress. I made my first wordress using Baskerville 2 theme and I would like it to be translated in French.
How does it work ?
It's quite well explained here: https://developer.wordpress.org/themes/functionality/internationalization/
Basically ensure that all plain text uses the get_text functions with a text domain for your theme: https://developer.wordpress.org/themes/functionality/internationalization/#basic-functions
Add code to 'Load' any translations https://developer.wordpress.org/themes/functionality/internationalization/#loading-translations.
Once you have done that, IF translations exist they will be used. THEN to get the translations.
This is also useful https://codex.wordpress.org/I18n_for_WordPress_Developers
There are a number of tools/plugins available to actually provide the translated texts. See here for some: https://make.wordpress.org/polyglots/handbook/tools/other-translation-tools/. Often the non-english users of a plugin or theme will voluntarily contribute a translation .po file to the developer.
I used to like the 'wordpress-plugin-codestyling-localization' as easiest for people new to translating, but sadly it's been not that usable for a few years. I don't have a preferred tool at the moment for actually translating the texts, but googling indicates various ideas from others for alternatives if non of the tools in the link above suit you.