The teenage defender arrived from Parma on the weekend.
Slot said ahead of Monday night's trip to Newcastle: "He is a good-looking guy, as most Italians! He has trained with us three times now I think.
“If you look at his transfer fee, you can expect that he is already quite grown up for his age – and that’s exactly what I saw.
“He comes in as an 18-year-old just playing with his new teammates as if he is here for longer. Impressive; if you look at how tall he is, fast, comfortable on the ball.
“Yeah, there’s a reason why we paid the transfer fee we did, because we see him as a bright prospect. Is that good English? And he had already three good sessions.
“It also tells you something about the team. If you come to this club, if you come into this team, you feel at ease from the start because it’s a very good and nice group to start your Liverpool career in.”