Pressing this button will update all of the values in the current workbook that come from the GL program. In some cases it may also fix cells with the following error: #NAME?.
There are three main reasons you would do this:
You know someone posted batches to the GL that will affect the balances in your workbook
You are about to print a report and want to make sure that you have the most current values
You just opened a report that you saved earlier and there are cells with the value: #NAME?