Metrics in Databox require a numerical value to visualize, however, there's a workaround you can use with Google Sheets to count non numerical rows.
Create a new column/row next to your non-numerical data and fill each cell with the value "1" if you want it to be counted, or "0" if you want to skip it.
If tracking form submissions, add a column with "1"'s to count submissions for each form.
Open Metric Builder and select your Google Spreadsheet as the Data Source.
Create a custom metric using the new column for counting (e.g. to count total submissions).
Set the Aggregation to SUM.
Name the custom metric and save it.
PRO TIP: A powerful method to fill cells in an entire column in a Google Sheet while ensuring all new rows are included is by utilizing the ARRAYFORMULA() function. Find out more in the official documentation.