Sajj

Official wording

Maintain nonfood contact surfaces clean. Thoroughly clean and degrease the cooking equipment and shelves above cooking equipment.

In plain English

Food was not kept cold enough, hot enough, cooled fast enough, or cooked or reheated to the right temperature. Bacteria grow quickly in the "danger zone" between 41°F and 135°F, which makes this one of the most important food-safety checks.