The value(s) that your check condition is evaluated against can be one of three types as listed below.
It's important to note that when evaluating your checks we use the raw value from the spreadsheet, without any formatting applied. For example if you have a cell with a price in that you have formatted as a currency when entering the value you should not include this formatting, just the raw numeric value.
Any piece of text.
Example: multiple words
Any integer or decimal.
A reference to a a single cell or range of cells using A1 notation that is prefixed with an equals sign.