This feature allows to block or unblock editing of or doing:

• All content and talk pages
• All content pages at once
• All talk pages at once
• All pages in some namespace
• User's own pages
• Other users' pages
• All pages belonging to a specific user
• Mentioning all users
• Mentioning specific users

The commands will be executed in order of placement.
So Block A* and then Unblock AA will allow AA but not AB

Examples:

Block namespace: Talk
Unblock pages: Talk:AAA

The user can edit articles, but only editble talk page is Talk:AAA

Block namespace: Talk
Unblock pages: Talk:AA*

The user can edit articles, but talk pages must start with "AA" to be editable

Block content pages
Unblock page: Wikipedia:Village pump*
Unblock page: Help desk
Unblock page: * noticeboard
...

The user can't edit content but can discuss it. Useful for users on probation for further unblocking.