Hreflang

Hreflang stops Google from showing your French page to English users, and it consolidates duplicate-language variants so they don't compete as duplicate content. The rules trip people up: annotations must be reciprocal (each page points back), you need a valid language-region code like en-GB, and adding an x-default catches everyone your specific versions miss. Get one direction wrong and Google silently ignores the whole cluster, so validate before shipping.