On a Facebook Page, a status update of the administrator's choosing that is highlighted and "sticks" to the top of the Page newsfeed until removed or replaced.

Why are Pinned Posts important to you?

Pinned Posts allow Facebook page administrators to choose specific status updates to promote by keeping them at the top of the page for new visitors. They are indicated by a small orange bookmark icon in the top right of the post, as seen below:

Facebook Pinned Post on Dell Lounge