[theme: zerif] navbar in different languages

Hello
sorry for my naive question, i’m new to this world.

i started a website using the nice zerif theme, i want a multilangual language and managed to translate everything i wanted, i added the flags i want and so on. but there’s one thing i’m struggling with more than the rest : the navbar.
how to do so that if english is activated, the main bar shows : “home, why us?, our services” etc, and if french is activated, it should show “Accueil, pourquoi nous ?, nos services”, etc.

i know i haven’t done a child theme, i’ll get to that once i understand a bit more why i need so:) (next update i guess!)

thanks a lot for your help