It's a fairly simple little tidbit - if you want to link to a specific post in this thread, and put that link elsewhere, it is possible that the link will break for one of several reasons - e.g., if you link to the thread and post number, the number can change if someone deletes a post above it. The permalink is a permanent link - it never changes, and is unique to that individual post.
hmmm - For something simple that sounds complicated!
It's just a link to the post!
Click the "permalink" and the link will appear in the address bar and you can bookmark it or copy it and paste it somewhere else.
hope that makes sense!
Seek, and ye shall find.
Inspiring, Informing and Connecting travellers since 1997!