A good review can be found in https://en.wikipedia.org/wiki/Dependent_and_independent_variables. In simple terms, if we have two variables A and B, we assume that the knowledge of one (say A) gives us information about the other (say B); typically, we think of the knowledge of A being independent of the knowledge of B.
In the case above: area name, employment rate, gross annual pay, population, average age, house prices. It is likely that one wants to predict house prices (dependent) as they depend on the other variables (independent variables): area name, employment rate, gross annual pay, population, average age.
If we know the name of the area, it's employment rate, gross annual pay, population, and average age, we expect to be able to determine the (average) house price in that area.
