You must separate a small portion of dough for the cohanim/priests whenever you make bread, rolls, or pizza of the Five Grains in certain quantities. This separated portion is called “challa.”
Note Since there is no Temple at present, we burn the portion of dough.
The requirement to separate challa applies to dough baked at home or commercially (such as a pizza shop), whether for eating on weekdays or for Shabbat/Jewish festivals. For more details, see Challa.