"You are in Amsterdam, Reem."
Translation:أَنْتِ في أَمْسْتِرْدام يا ريم.
It is a standard in fact. Even in everyday speech (dialects) we do use Yá often and I can't really formulate a specific rule for dropping it out. So, it's better to think of it as a standard thing to use it before names when calling someone.
In fact, in classical Arabic and in some common expressions, the noun after Yá would be dropped (for some eloquence or adding some sense of poetry in some sense) - and the Yá article is kept. One common expression I can think of from classical Arabic with such usage is يا هل ترى (yá hal tará) or (yá hal turá) - both are correct, which translates to something like (O, (subject), do you presume...) - the subject here is proposed and dropped, you can equate it with (Man), (Woman), or anything you are supposedly talking to. Don't worry about this though for now, this is way deep into literature and it's not the common thing used by people in everyday (even though they might sometimes use the expression without understanding it linguistically).