This is for a page you want on your website but not open to everybody: trade prices for regular customers, notes for staff, a page of files for a client. Anybody without the password sees the page title, your short line if you wrote one, and a box asking for the password. Nothing else.
The words on a locked page are not sent to somebody who has not got in, so they are not hidden from view, they are simply not there. Search engines are told to leave the page out of their results.
One page at a time. Your home page cannot be locked, because a website whose front door is locked looks broken to everybody else. There is no lock for a whole site.
The password is asked for on every visit. If you change anything on a locked page and publish it, it stays locked.
Step by step
In the editor, open the page you want to lock.
Press "+ Page" at the top, then Password.
Type the password twice. It needs at least 6 characters.
Add a line for the people who should get in, if you like.
Something like "Trade customers: ask us for the password." It is the only thing a stranger sees besides the title.
Press "Lock it". It is live in about a minute.
Open the page in a private window and try the password yourself.
If it does not go to plan
How do I change the password?
Open the page in the editor, open the page menu and press Change password, then type the new one twice. The page stays locked the whole time. The old password stops working straight away, so tell the people who use it.
Somebody says the password does not work.
Check the capitals: passwords are exact. After 10 wrong tries in a few minutes the page asks them to wait, so they should give it five minutes before trying again.
The Password button is not there.
You are on the home page, which cannot be locked, or your role on the site cannot publish. Only somebody who can publish can lock or unlock a page.
I moved back to the $10 plan. What happens to my locked page?
It stays locked. You cannot lock a new page without Pro, and you can always take a password off.