In your settings, you can set your preferred languages - since you’re on lemmy.world this link should take you there. You can hold control down to select multiple options if you’re on desktop (and mobile should have a selection box pop up).
Though be sure to keep “undetermined” enabled, otherwise a lot of stuff will vanish. Also note that this only works for posts/comments where people have actually selected the correct language (if someone posts something in German, but marks it as English for example, it will still pop up).