A free spin is essentially an offer that a casino gives to its players to spin the reels free of charge and have the opportunity to win real cash. The free spins may be given to both new and current customers, and it's one way to reward and encourage them to continue betting.
Switzerland is at the heart of Europe, at least in terms of geography. Famous for its political neutrality, it hosts several international organizations. Gambling in bricks-and-mortar casinos has long been a tradition in Switzerland, but online casinos are formally illegal. In practice, it is possible for the Swiss to play in international mobile and online gambling casinos.