Complex sentence: He made his professional debut on 2 May 1937 with A.S. Roma at age 15,9 months and 6 days (the youngest debut in Serie A history) and played also in Serie B with Atalanta B.C., Inter and S.S.C. Napoli.
Split into simpler sentences: He made his professional debut on 2 May 1937 with A.S. Roma at age 15,9 months and 6 days (the youngest debut in Serie A history). He also played in Serie B with Atalanta B.C., Inter and S.S.C. Napoli.