You may need to read the content of your Microsoft Excel document in a document library on the SharePoint Online site. For this, you can use the Excel Services REST api, which is served from /_vti_bin/ExcelRest.aspx.
For use, of course, you first need a Microsoft Excel document. Prepare a Microsoft Excel document that contains a table and upload it to your document library in SharePoint Online.
Then you can get your document content in json format with a URL like the one below.
“TEST1RANGE” is my table’s name on Excel file.
You can find a full sample on my Github repository.