"Variables" refers to concepts that firms and organizations in general are interested in "explain" and forecast.
In regression analysis there is a clear distinction between:
1. the "dependent" variable, and
2. "independent" variables
The dependent variable is the variable to forecast or explain. For instance: sales, inventories, interest rates, and inflation rate.
Independent variables refer to variables
that, it is believed by the analyst (manager, statistician, or
business person in general), affect and somehow determine and
explain the dependent variable.
For instance, the price of a product, the amount of dollars spent
on advertising, the level of income, and the price of substitute
products, are (independent) variables that could explain the behavior
of sales of a product (like cereal, tooth paste, or automobiles).