Leave and keep are quite different words in any language. This a bad translation. Also I suspect your bag is like your body parts - it means "your bag".
You're right, it's "your bag" and this was a bad translation.
But in Portuguese deixar can mean let, leave, keep and allow (and maybe more):
Leave me alone - Deixe-me em paz
She keeps her hair short - Ela deixa o cabelo curto
Let me try - Deixe-me tentar
They didn't allow me to get in - Não me deixaram entrar
That's no surprise. In Spanish "dejar" also behaves quite like that. And in French, "laisser", and in Italian, "lasciare". It doesn't mean that "leave" and "keep" have the same meaning, but only that these meanings can be represented by the same word in those languages.
"Your bag" is certainly a good translation, but "the bag" is just as good.
Being a "bag", it might be either obvios that you are talking to the bag's owner, or not.
Idiomatically, we also use "deixar" as to "keep", in the sense of a place where we keep something regularly.
In this case the "abandon" idea contained in "leave" is not really present.
Can't speak for England or the US, but it would be normal to say "leave" in this situation in Australia. e.g "I leave my keys by the door."
Also correct in American English. Though my in-laws in Pennsylvania say 'let' where I would say 'leave'. Influence from Pennsylvania German?
I answered "Don't let your keys in the bag" and Duo has considered as wrong. Is it right?
let in English is permitir, that is to permit or give permission. However, American use of let can be very similar to Portuguese. For example, Let her in peace = deixe ela em paz. But it doesn't work in your example.
Some dialects of American English use let, like the Northeast. In the South, we say leave instead of let. Since I am from the South, I always translate deixar as leave.
- Deixa is the imperative for tu (affirmative only)
- Deixe is the imperative for você
- Não deixes is the negative imperative for tu.
So, in affirmative sentences, you can use both:
- Deixa comigo = Deixe comigo = Leave it to/with me
In negative sentences, though, "deixa" is not correct:
- Não deixes que isso aconteça = Não deixe que isso aconteça = Do not let that happen
I thought about that afterwards and wanted to edit the comment, but I was on my way out shopping; you saved me the job, thanks.
It doesn't make sense to me either. I get the impression that the keys might make their way into the purse all on their own.
The expression "Don't let the dog out" comes to mind. (It means "Don't allow the dog to go outside.) Or "Don't leg the dog in" (It means "Don't allow the dog to come inside)