Today this is the side entrance to the backyard of a kindergarten in Villach. The inscription above the portal is partially unreadable, but it begins with “ORATE ET VIGI”, obviously a variation of the more common “vigilate et orate”, “watch and pray”, from Matthew 26:41.
It could be the last surviving part of a former monastery, it could be an entrance to former gardens of the Franciscan monastery not far away. It could also have been torn out of context by a former proprietor of the building. I don’t find anything about it online. It looks genuinely old though.