How to get length of the google sheet column before calling column data

How can I know a length of column in google sheet before calling a column data, so that there is no blank data in the variable. I show this data in the spinner but it shows the blank data also.

Which data???

First create extra table in Google sheet or airtable then create colum and set your total rows length in value box… Then first call your length column by get cell or row then store value in variable…