(Probably among many other things) this abbreviation stands for 'Schweizerische BundesBahnen' (Swiss Federal Railways).
Famous for punctuality and service, the SBB are one of the few things the Swiss can really be proud of. Not too many other countries have a network of railways as dense as them. Being a small, crowded place, there's no space for 5-lane freeways and thus many people prefer trains over traffic jams. SBB is the facilitator, they get people almost anywhere quickly and easily. People read newspapers while driving to work instead of swearing at the car ahead.