What is density? what does it tell you about the substance

(1)Density is the degree of compactness of a substance.
(2) Density is the degree of consistency measured by the quantity of mass per unit volume. 

basically, density is mass spread out over volume. Some examples are oil and water. Oil is more dense than water so it rises on top of the water when they come in contact like in oil spills.

You can still be friends with each other. you don't have to date since he likes someone else. just stick to being friends for now