When you log into seller central, you can click Catalog at the top left and enter the ASIN you want to look up. It will then pull up the product and say if you're able to sell, or if you need to request approval depending on the condition. If you do need to request approval, it will let you know what they want to see in order to approve you.
For more details, please check out the course lesson titles "How To Know If You're Gated" in the "Product Research in Depth" section of the course.