You use 'Ils' when it's a mixed group and 'Elles' when its a female group.
Is this why 'elle' is singular when we are actually talking about plural people in this sentence?
The original sentence has elles not elle. It's an error to use elle here, although apparently Duolingo accepted it at one point.
I never understood how to distinguish "Elle" from "Elles" and "passent" fron "passe". it also happens with other words
By sound, you cannot. You have to rely on other things, such as logic and context.
It wouldn't make sense if it were "She spends the night together" - together with whom?
plural articles, plural verbs, plural adverbs or adjectives or singular.... are the clues.
Elle passe is singular, and elles passent is plural. As neverfox said, you cannot tell the different in the way they sound. You have to work out which one it is by context, or in this case, logic that if they're together it must be plural.
it could be about more adult things or it could be about like a slumber party or just a matter of convenience, like two female relatives crashing in a bed together for whatever reason (not enough beds, sisters who do it anyway, etc)
Mm, I think "spend the night together" is only barely euphemistic. You know what that means.
Thanks for the expression.
I like "au réveil" or "le matin" here, which I would translate to "in the morning".
Then you'd get "she does the walk of shame in the morning", whereas with "du matin" your sentence makes it sound like "she does the morning walk of shame" or "she does the walk of morning shame". (Or perhaps that's what you intended?)
Alternatively, there's "le lendemain matin" or "le matin suivant" for "the next morning".
Because it is past tense, and the French sentence is in present tense: They spend (are spending) the night together.
It doesn't quite work. It implies staying the night, together, at a particular place already mentioned. "Passer la nuit ensemble" is independent of any consideration of the place where the people might be staying.