What is Unit ?
Unit is noun 1. one part of some- thing larger If you pass three units of the course you can move to the next level. 2. one piece of furniture, such as a cupboard or set of shelves which can be matched with others The kitchen is designed as a basic set of units with more units which can be added later. 3. the amount used to measure some- thing Kilos and pounds are units of weight. 4. a specialised section of a hospital She is in the intensive care unit. The burns unit was full after the plane accident. 5. a single number less than ten 63 has six tens and three units.
source: Easier English, Student Dictionary Upper Intermediate Level