Yes, select the email you wish to add by tapping on the picture or big blocky letter, then tap the icon at the top that looks like a folder. You may select a label there.
From there it seems you can only select existing labels. I don't see a place to add new labels there.
doug
did you get answer to Doug that is my question also he do you open new folder on gmail app on android
Guys,
Not sure if you have worked this out but if you use the "inbox by gmail" app you can do it in there I just tried it and it worked. That's the app with the blue envelope.