Here is something odd - the wiki translation of the thing omits “quo”. Well, it also omits “et”, but that is understandable when one is carving on a rock.
SetPQuoA
Nowadays, SPQR can mean "Siempre Potenti Questi Romanisti," or "Sono Porchi Questi Romanisti," The former is a positive assessment of the AS Roma Serie A soccer club (Forever Powerful These Romans"; the latter is an insult hurled by Lazio fans at their Romanisti enemy fans: What pigs these Roman fans are. A little Italian soccer lore here.
S P Q R
I know it has to do with the Roman Empire but sadly do not know it's meaning. Thanks in advance.