The 3-dot menu offers context sensitive options. In mail view it offers : Reply Forward Delete Archive Mark as Unread Move Star Mark as Spam More Options… Print Later+
Below are the bottom bar icons and their descriptions: Mail Compose More
On the top bar 3-Dot Menu you have these options: Search Multi Edit Settings Add Account Send Feedback
Within an email you have a bottom bar with the following icons: Later+ Mark as Done Trash Reply All More
Swiping right the email reveals three options: Done which allows you to mark an email as Done, Later+ which allows you to select a deferring time from a menu, and More where you can find additional options. Swiping left the email reveals three options: Mark Read / Unread, Archive, and Delete.