You can easily hide the headers of rows and columns and show them again. Use the Hide/show headers button for this purpose.
After that, the blue headers that contain numbers to specify rows and letters to mark columns will be hidden:
To show the headers again, click the Hide/show headers button again.
The grid lines of the sheet can be hidden as well, if needed. To hide them, click the Hide/show gridlines button.
This is how a sheet with content will be displayed with grid lines hidden:
To show grid lines again, click the Hide/show gridlines once again.