The Siemens 5SL6620-6BB is a miniature circuit breaker rated 400 V with 6 kA breaking capacity, 3+N poles, B-curve trip characteristic, and 20 A rated current — the Italy-market version.
Snap-on DIN rail mounting for standard 35 mm rail, 3+N-pole form factor occupies four modular-width positions (72 mm at 18 mm per pole). The Italy version designation typically affects labelling language and possibly the neutral position (left-side neutral on some Italian-market boards) — verify the neutral configuration against your existing distribution board before committing the order.