Once a file is uploaded, you can preview the original file and convert it to Google Sheets.
Double-click an uploaded spreadsheet.
While previewing a spreadsheet, you can choose to comment on it, print it, download it, and more.
Click Open with Google Sheets.
Though you're viewing the document in Sheets, you can see by the file extension that it's still in the Excel format.
Click File on the menu bar.
Select Save as Google Sheets.
A new tab opens with the converted spreadsheet, and if you switch back to the Google Drive tab, you can see that the original Excel spreadsheet and the converted Sheets spreadsheet are both saved to Google Drive.