What does it mean to let bread dough rest?

It simply means to stop mixing, beating or kneading the bread dough for a period of time, often 15 minutes. This resting time allows the flour to absorb the moisture that has been added, which is particularly important for whole grain flours. The dough can rest in the mixing bowl or on the kneading surface, but it should be covered with a damp cloth to prevent the surface from drying.