You can use a range name in a formula to refer to data you want the formula to use. More power with formulas describes all the basic parts of a formula and the different types of formulas.
If you delete a range name that a formula uses, your spreadsheet replaces the range name with its associated range address. For example, suppose that SALES is the name of B14..H14, and that your sheet contains the formula @SUM(SALES). If you delete the name SALES, your spreadsheet changes @SUM(SALES) to @SUM(B14..H14).