Question

what do you mean by data validation in excel

Answer 1

Data validation is a feature available in Microsoft Excel. It allows you to do the following: 
Make a list of the entries that restricts the values allowed in a cell.Create a prompt message explaining the kind of data allowed in a cell.Create messages that appear when incorrect data has been entered.Check for incorrect entries by using the Auditingtoolbar.Set a range of numeric values that can be entered in a cell.Determine if an entry is valid based on calculation in another cell.

Answer 2

data validation means that in a cell u cannot write the data which is not set already