Music - "a hit single"
A single song (not an album) that has become successful
In Wiki I found "un nuovo singolo di grande successo" QUA.
Baseball - "a hit single"
I can imagine a very excited announcer saying "...a hit...single..."
Baseball - "his hit singles"
The person who hit the ball has gone to first base QUI - "battuta valida da una base, il singolo"
"...la sua battuta è un singolo" ?
"...il suo colpo è un singolo" ?
"...il suo hit è un singolo" ?
Music - "his hit singles"
He has had many "singles" that have been successful
...i suoi singoli di successo. ?
Ma, chiaramente abbiamo bisogno della frase intera....
But in baseball, single is also a noun, non è vero? e.g., 100 of his hits last season were singles. He also hit 40 doubles, 6 triples, and 15 home runs.
I hadn't originally thought about "his hit singles" with singles as a verb, but I see it now -- grazie, Tim. "His hit singles" could still be a reference to music, though, e.g., "All of his hit singles occured in the early 1960s."
Maybe ayoung202 will come back to clarify the context sometime.