Pizza dough is much easier to reshape if you give it time to come to room temperature first. This is because it is made from gluten, which is less flexible in colder temperatures.
If you try to stretch out dough that's too cold, it will likely keep snapping back to its original clumpy shape. This could lead to overhandling the dough, making it tough.
If your pizza dough has been sitting in the fridge, let it sit at room temperature for about 30 minutes. Frozen pizza dough will need a 3 to 4-hour thaw.
If you're making pizza dough by hand, you should ideally let the dough sit out just after the bulk fermentation period, as longer fermentations draw extra flavor from the dough.