The Poll block shows the current polls that are set to be shown on the frontpage. Depending if the user has voted already, it shows the result or the questions, and a link to the comments if applicable.
Strictly speaking, this block is not part of Geeklog itself, as it is actually provided by the Polls Plugin.
The polls shown depend on the permission of the current user. Only polls are shown that are set with "Appears on Homepage:"-switch.