As the title says.
Which page is that? Can you provide a URL and a screenshot?
Those are the character count changes (addition or deletion) of the edit in question. So you can see where smaller, probably insignificant, edits occurred, large additions to a page (spam vandalism or someone adding content?), or large deletions to a page (page-blanking vandalism or moving content to another page?).
Ahhh, thanks.