What does “secured” mean in Adobe Reader?

It usually means the document has security settings — either an open password or restrictions on printing/copying/editing.

Can you unlock a scanned secured PDF?

Yes — the protection is removed the same way. Note we remove the security, not the “scanned” nature of the pages.

A PDF marked “secured” can mean two different things: it needs a password to open, or it opens but blocks printing, copying or editing.

Knowing which you’re dealing with tells you the fastest way to unlock your own file.