The Permissions tab allows you to view a policy summary, which gives you a high-level breakdown of the permissions, which are broken down into the Service, Access level (such as read/write), Resource, and Request condition sections. From this tab, you can also view the policy in JSON format by clicking on the {}JSON tab. Finally, you can edit the policy by selecting Edit policy:
This is a great way to gain a quick view of the permissions associated with the policy.