What is this switch called?
This is a DPDT-Double pole, single throw
Vertical Push Switch, as you can see here.

You can check a datasheet example, datasheet

Its two switches inside one package.







simulate this circuit &ndash; Schematic created using CircuitLab

In your case the pins 1-4, 2-5 and 3-6 are connected togheter.

The pins 1 and 4 are the Normally Closed, and the pins 3 and 6 are the Normally Open, the pins 2 and 5 are the commom pins for each circuit.