Excel's VALUE function has only one argument: where a is the value stored as text that you want to convert into a number.
Other versions of Excel may work differently. Extracting, parsing, or splitting data using TEXTSPLIT is an easy ... curly brackets around the entire set of delimiters, separate each delimiter with a ...
If you've used data validation in Excel before, you probably selected the relevant cells, clicked "Data Validation" in the Data tab on the ribbon, and created the rule in the Data Validation dialog ...