ELI5: What does it mean when people say there’s no proper translation from a non-English word to English?

You see it quite often when someone will say ‘there’s a word for that…there’s no direct translation but it’s loosely like…’ then proceeds to give it a translation.

I saw one recently of kummerspeck, I think the commenter said it was ‘food you eat when you’re sad’ or ‘grief bacon’.

I would also like to preemptively apologise for my ignorance.