Hi washalsi,
The Sheet is a blank canvas on which tables, text boxes, graphic objects and charts are placed Like a baseball field (ideal, not one bounded by practical considerations), the Sheet has only two boundaries, one at the top (third base line), the other on the left side (first base line). There is (theoretically; in practice, it likely depends on available memory and the capabilities of the platform) no right side boundary and no bottom boundary to the Sheet.
You can decrease the amount of space your objects occupy (and the number of pages it will take to print your document) by moving things upward and to the left. You can check how the document fits on a page (or several pages) using Print View (Press command-P or go File > Print...; exit Print View by pressing escape or clicking Done at the bottom of the dialogue), or you can show the Rulers to give an indication of where your project sits on a page.
Regards,
Barry