Thanks for posting here and welcome to the community!
Some nodes or operation types (like the Google Sheets Node - Update Row) will not return anything because they only perform an operation. You can think of it as a function in programming that does a job but does not return anything.
You should be able to see your updates made in the Google Sheet itself.
If you’re using another operation on the Google Sheet node (e.g. Get Rows) You will have items in the output pane, because this operation is programmed to return data.