I assure you that 99.99% of all toggle switches work as I explain below. The mechnical parts inside are designed to connect the terminals just as I explain here.
Perhaps there are some Rube Goldberg switches out there that work opposite of this but they are few and far between and I assure you that the normal switches
you buy will work as described below. One exception worth mentioning is that if a double throw switch is specified as ON-OFF-ON is means that there is a special
middle position in which the center pole(s) does not touch either of the other poles. This is known as a "center off" switch. The normal double throw switches are
specified as ON-NONE-ON which means they have no "center" position and are always in contact with one of the other pole(s).