Welcome from Scotland, Micaela!
I can tell you it's an Italian bike: the rims (cerchi) were made by Limone &co, a quick Google shows Limone being a town in Piemonte near Lago di Garda well known for mountain biking. Limone is also near Torino.
In Torino the saddle bag was made,
here is a link for one similar for sale-click on the blue bit, it's in Italian but you may be able to understand.
It stands to reason, a lot of Italians emigrated to Argentina, one of them brought their bike with them!
Is there not a logo on the front of the bike? Can you take a picture from the other side?
The bike is very old, but the tyres don't seem so old.
Ciao!