There is a review of your hub before it gets featured and this is called the Quality Assessment Process. Once you publish your hub, it will go through this process and there will be a pending symbol beside your hub in your account while it's undergoing the assessment. The assessment usually takes about 24 hours or so.
While your hub is pending, it is published but not featured, which means that search engines won't be able to see this hub and only those you give the link of your hub to can see it. You can also set your profile settings to show all your hubs, whether featured or not featured.
If your hub passed the Quality Assessment Process, then it will become featured and you can see the appropriate symbol in your account beside the hub. If your hub didn't pass, there will be another symbol that you can see. You can just edit your hub so it would go through the process again so it can be featured.
You can check these links from the HubPages FAQ and learning center to find out more about the Quality Assessment Process including the criteria and rating scale. Here are the links: https://hubpageshelp.com/standards/Learning-Center and https://hubpages.com/faq/#quality-assessment . Hope this helped.