If you freeze something, you lower its temperature below 0°C, causing it to become cold and often hard, and if something freezes, its temperature goes below 0°C:
Water freezes to ice at a temperature of 0°C.
freeze hard The ground had frozen hard.
freeze solid The river used to freeze solid every winter.
We had to play the game in driving rain, but at least the pitch wasn't frozen.
freeze over When the lake freezes over (= turns into ice on the surface), we can go skating on it.
freeze up Our pipes froze up (= the water in them turned to ice) several times last winter.
The weather forecast says that it is going to freeze tonight (= that the temperature will be at or below 0°C).
freeze to death Without a sleeping bag, you would freeze to death (= become so cold that you die) out there on the mountainside.
to make food last a long time by storing it at a very low temperature so that it becomes hard:
I'll freeze any food that's left over.
Most soups freeze (= can be preserved by being stored at a very low temperature) well.