In a previous sentence "nos" meant "ourselves" but here "vos" does not mean "yourself" why ?
Vos means yourselves. The translation here is missing it. In English, the verb to wash is almost always used transitively, such as "He washed his socks with soap and water." Or, "Employees must wash their hands after using the bathroom." When it is used reflexively, as in this example, we must use a reflexive pronoun. The correct translation is *"Where do you wash yourselves?" It's been reported and will soon be updated.
Btw, the report box had only the following options:
The audio does not sound correct.
The dictionary hints on hover are wrong or missing.
The Latin sentence is unnatural or has an error.
Why is it that sometimes there are up to five options, but sometimes only three? And of course it's one of the missing options that you need...