When you work in Stackbit, you're working in a preview state. This means that any changes you make are not immediately shown on your live site, but must be published.
When you're ready to publish your changes, click the Publish button in the top right corner of the page editor.
This will open the publishing menu, which lists the pages that have changed since you last published. Click Publish pending changes to start the publishing process.
Because your site is a Jamstack site, the site must be rebuilt and deployed before the changes you made to the content in Stackbit will show up on your live site.
The publishing buttons will be in an in progress state while your site is being built and deployed.
If you want to follow along with the technical details, you can view the deployment logs in the bottom right corner of the page editor.
The URL to your live is shown in the publishing menu. Click this link to open your live site in a new tab.