The term above the fold describes the area on the monitor that is visible without scrolling. It originally derives from graphic design of newspapers. The most important news should be placed above the fold to be shown on the first page of a newspaper to highlight the relevance of an article.
This concept is of great relevance in terms of Search Engine Optimization (SEO). The visible area on a screen highly depends on the size of the monitor and the chosen resolution. Google for example normally displays about 5 results above the fold.