"Pole" refers to the number of pairs of contacts there are on the switch: Single Pole is one pair, Double Pole is two pairs. Sometimes you will see Triple Pole; three pairs.
"Throw" refers to the number of switch contacts for any given Pole pair in the switch. Single Throw is one set, Double Throw is two sets. I do not remember seeing "Triple Throw" switches, although some may use that to refer to Double Throw, Center OFF switches.