Good question.
A direct variation equation is an equation where as as one variable changes, the other changes a certain amount. So if your two variables are x and y, as x changes, y changes a certain amount based on how x changes.
It usually is an equation like this y=(some number)x, where the number is how much y caries with x.
So if you are given an ordered pair like (6,2), where y is 6 and x is 2, then you want to set up an equations where 6=(some number)*2. In this case the number would be 3, so the equation would be y=3x.