Freezing is lowering the temperature below zero Celsius. In anything made of water, the procedure creates ice crystals that poke the cell membrane, making a lot of microscopic holes than quickly leach the inner contents of the organism by differences in osmotic pressure. This kills the cell by "bleeding to death".

As bacterias are cells with membranes in principle they are killed when frozen, so far, so good...

... but this is just the general case. Not all bacterias have being created equal and there are thousands of species.

Some are extremophiles and store sugar or other substances that act as an antifreeze, so can decrease the temperature of freezing and remain "liquid" under zero point. They can stand much lower temperatures before being killed (by freezing). Is just that they are killed at -25C instead -5C, but the killer is still a tiny ice dagger.

And some bacteria have evolved an outer protective gelatinous capsule, made partially with "sugar", that is not easy to pierce, so they can alter their osmotic pressure and stand more osmotic stress.

And finally, some will just die, but not before creating a inner spore devoid of water that can stand the cold or dry until rehydrated. No water, no ice.