It is the first paragraph the gives you the correct understanding.
The start of the Mark section (few line before the line your quote) is:
Jumping to a mark can be done in two ways:
1. With ` (backtick):
The cursor is positioned at the specified location
and the motion is exclusive.
2. With ' (single quote):
The cursor is positioned on the first non-blank
character in the line of the specified location and
the motion is linewise.
Unfortunately, you also need to read the context to have the right understanding of the doc.