This doesn't tell me what changes it's going to discard. The word "uncommitted" should probably be in there somewhere, and I would use "delete" instead of "discard" for a file operation. As in "Delete all uncommitted files and file contents and set them to the last git commit?". Plus a list of changes that will be made, like:

- delete a.txt

- delete b.txt

- delete 123 changed lines from c.txt

As it's worded it's quite vague what's going to be discarded from where and how. Presumably if you know which button you clicked, it's more clear, but if you mis-click and don't know what you clicked, you can quite easily make the same mistake.

Finally, he's right that programs shouldn't be deleting files without a way to recover them in 2017. That operation should require the same level of directed intentionality as launching a nuclear missile.