:) I'm often pleasantly surprised at what English expressions are also used in Italian.
Really we would say," My birthday is ON Monday", if you mean next Monday If you want to say that when your birthday eventually comes it will be on a Monday, we say just that: my birthday falls ON A Monday.
Exactly the same in Italian.
in Polish too
In Italian, would this translation imply that my birthday falls on a Monday, or that it falls on this Monday?
"my birthday falls on a Monday" is "il mio compleanno cade di lunedì"
"my birthday falls on this Monday" is "il mio compleanno è lunedì (prossimo)"