Cells in a worksheet can contain either numeric values, text values, or error values. (Some people will mention dates and times as another type of value, but these are nothing but special types of numeric values, as are Boolean values such as True and False.) In some instances, you may need to know whether a particular cell contains a text value or not.
You can use the ISTEXT function to make this determination. For instance, if you need to know if cell B7 contains a text value, you would use the following formula:
The function returns either True or False, depending on the type of value in cell B7. ISTEXT takes a single value, normally a cell reference of some kind. This should be a reference to a single cell; if you use a reference to a range, then the function always returns a False value.