In short, a Legacy URL allows you to redirect one link to another link it comes in handy in the instance that you delete a page and create a new one with a new name, you can use a Legacy URL to redirect users to the new URL.
|Helpful Article: What are Legacy URLs?|
1. Select Settings (gear icon) in the Dashboard navigation bar.
2. Select Legacy URLs.
3. Select Add Redirect.
4. Complete the first field with the URL that users will enter in their browser.
5. Complete the second field with the URL that the users will actually arrive at.
6. Select Save.
Redirect from: Enter a legacy URL path to redirect from. This should not contain a domain name; rather it should be everything after the domain name.
e.g. /my-OLD-page.html or /OLD-page
Redirect to: Select content or enter a URL to redirect to.
e.g. /my-NEW-page.html or /NEW-page
Complete URLs work as well, e.g. http://google.com/