I am almost at wits end with the seeming resistance to do web searches to get the answers to commonly answered questions. This should be done FIRST.
A web search, https://duckduckgo.com/?q=keyboard+shortcuts+gmail,
on [keyboard shortcuts gmail] returns, as its first item: Keyboard shortcuts for Gmail - Computer - Gmail Help
Questions about navigating the Gmail website with NVDA (or any website with NVDA) are perfectly appropriate. It is, however, a very simple matter to use web searches to find out virtually anything you need or want to know about Gmail's features, regardless of what particular feature it is you wish to know about. Those aren't NVDA-related, either.
Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763
Puritanism: The haunting fear that someone, somewhere, may be happy.
~ H.L. Mencken