I think it very much depends on the context, though. I would argue that the icons in this screenshot are very easy to understand the meaning of.
The top left is a close icon, then going from right to left of the group in the top right, I'd say that's a download/save icon, then delete, then Google's commonly used vertical ellipsis that brings up more options.
I've never even seen this Material Design app before and have never touched an Android L phone either, but I think I'd be confident knowing what the icons did if I used it.
The silly little geometric shapes at the bottom, which I believe are system-level controls... I have no idea what those mean.
Well, as if to prove my point, I believe it's an "archive" icon, not download/save...