Sourcing data from Google Sheets works in the same way as every other external data source before. No data feed is created for its own sake. They should do something.
First look at the App you want to source with the Data Feed. What type of input does it require? You find this in the Data Feed Requirement of every Data Feed enabled App.
In the example of the Menu Board – Basic App, it requires input in the form of two text fields – one for the Item Name and one for the Currency, this one is optional – and of one number field.
Your Google Sheet must have these fields at a minimum.
Select Get link.
If you need help with setting your Google Sheet shareable, go to Google Support for further reference: https://support.google.com/drive/answer/2494822