Games in roblox are comprised of Places. A place can be thought of as a level; it contains level geometry, user interfaces, game logic, all the pieces that make a level in your game. Every game must have at least one place in it. When selecting file > new in Studio or selecting a template, you are creating a new place. After editing a place it can be published as part of a new game or can be added to an existing game.
Start Place: Every Game in roblox must contain a Start Place. This is the place players will first enter when they play a roblox game. From there, players can be moved to other places in the game using the teleport service.
By default if a place is published to a new game that place will be designated automatically as the start place. If more places are added to the game, the start place can be changed either through the game explorer in Studio or through the game's configuration on the roblox website.