Click to the left of the section heading.

The section changes to

and the contents are displayed.

To expand all sections in a worksheet: On the ribbon, from the View tab, click the Sections dialog box launcher, and then, in the Sections group, toggle Expand All Sections. The contents of all sections in the worksheet are displayed.

To expand all sections in a help page: On the ribbon, from the View tab, click the Sections dialog box launcher, and then, in the Sections group, toggle Expand All Sections. The contents of all sections in the help page are displayed.