When you print a worksheet, Excel breaks up the pages based on the margins you have selected, the column width, the scaling options, and other page setup selections. Excel also automatically inserts page breaks when you define a print area. Page breaks appear as dashed lines on the worksheet. They aren't always easy to see, unless you're in Preview mode or if you have Excel's gridlines turned off (to do so, choose Tools, Options, display the General tab, and deselect the Gridlines check box).
With Excel, you can insert two types of page breaks: vertical and horizontal. A vertical page break will break the print range at the current column. A horizontal page break will break the print range at the current row.