It turns my chapters into these cute little index cards all tacked up there on the bulletin board, with a synopsis of each. (And I love those little pushpins.)
With the chapters lined up on the left side there like this (index cards big; or index cards little).
It shows my whole manuscript in this way-cool outline form:
Or I can see the manuscript on the screen like this, with everything else blacked out, and I can just scroll thru it:
It does lots of other way-cool things. You can move text around like crazy and insert all kinds of notes and highlight and annotate and footnote and save snapshots of drafts. You can even sort chapters by POV or keywords and, and, and..... This is the coolest software ever.