All of the ability holder's normal-type attacks become ice-type attacks. They also receive an increase in power of 20%*, and ice-type Pokémon receive STAB* from these moves.
Refrigerate is similar to the following abilities in that they turn Normal attacks into another type with a reduced power boost; Aerilate for Flying, Pixilate for Fairy, and Galvanize for Electric.
Normalize was turned into a reversed variation of these abilities in the seventh generation.