Perhaps this is more of a UX question, but anyway: it's a progress indicator, or more specifically, an indeterminate progress bar.
This is how it's intended to look like:
It's purpose is to let you know the system registered your click on the save/edit button, but it needs a while to save the changes or prepare the edit mode.
There's no need for a confirmation field for an account that doesn't involve any identity verification other than a working email address. If you mistype the password when you set it, you just have to use the "forgot password" process to correct it to what you want it to be.
If the site had a more involved process for resetting a password, then ...