Changing the pagination settings for a paragraph allows you to specify things like "A chapter heading must always start a new page" or "A figure paragraph should span both columns of a two-column document". The options you can select here are:
Start: This allows you to specify specific staring places for a paragraph. For example, if you wanted to have all new chapters start at the beginning of a new page, you would select Top of Page. Other options include: Top of Column, Top of Left Page, Top of Right Page, Anywhere, & As is.
Keep With: This allows you to specify that a paragraph remains connected to the paragraph before or after it.
Widow/Orphan Lines: This number indicates the number of lines of a paragraph that have to remain together alone at the end of a page (orphan) or the beginning or the next page (widow).
In Column: This places the paragraph in a text column (standard).
Run-In-Head: This creates a run-in heading (not on
a separate line from the following text). You can specify punctuation which always follows the heading (like a period or a colon), which will be added unless the header text has its own punctuation.
Side Head - Alignment: This creates a side heading, typically placed to the left of the body text. The alignment specifies how the header will be placed with respect to the body; "top edge" will align the top edges of heading and body, "last baseline" will align the bottom of the heading with the top of the body, and "first baseline" will align the
bottom of the first line of the heading with the top line of the body.
NOTE: if you want to use Side Heads, make sure to turn on "Room for Side Heads" in the under Format -> Page Layout -> Column Layout
Across All Columns: This places the paragraph across all columns of the document (though not across the space allotted for Side Heads)
Across All Columns And Side Heads: This places the paragraph across all columns of the document, as well as across the space reserved for Side Heads.
As Is: You would use this option when you have selected paragraphs with different pagination properties, and you want them to keep the properties that they currently have.