Well spotted! Traditionally translated as “On with the motley, the paint and the powder”: Canio the clown has to go out and make the crowd laugh even as he’s realised his wife is off with another man. If memory serves, the recording by Caruso was one of the first worldwide hits for a gramophone record.
Only if it’s a featured solo. More than one voice or just a quick bit aren’t arias. The rest are duets, trios, choruses, etc. In many cases, if an opera has many solos one of them gets singled out as “the” aria. So if someone refers to “the aria” of Madam Butterfly, then it’s just the most famous aria they are talking about. That confuses things sometimes.