Changing the name of your website page is easy!
Within the editor, expand the Pages and navigation panel on the left and find the page you want to rename. Click on the settings wheel next to the page title and select Rename:
Insert a new page title, save the changes, and update your website for the changes to reflect online.
When changing the page title, the page URL will also automatically update
To change the meta titles of your pages, refer here: Website builder: Meta titles and descriptions of pages