With "you" on its own,one can't easily discern whether 2nd person singular or plural is implied. This problem, like so many others, does not exist in other European languages.

In the context of "guys", "you lot" this is true, at least amongst the European languages I know a bit of. However, the problem reappears for some contexts in French, German, and Czech (at least) with the use of the 2nd person plural for the polite form.
Does anyone know of a list (or can we compile one between us) of languages which use the 2nd person plural as a polite form for the singular. Italian and Spanish have polite forms but they are distinct.

Please correct any inaccuracies in the above. As if you needed any prompting .

Rod