Question

Which process centers the spreadsheet's content on the page?

Answer 1

select the Horizontally and Vertically boxes in the Margins tab of the Page Setup menu

Answer 2

The process that centers the spreadsheet content on the page is called page layouting. Which is located on the page layout tab. Page layouting is done by choosing the custom margine of your page content. The margin determines how far from the left and right your contents are.