In its most simple form, braising means slowly cooking something in a bit of liquid at a low temperature. I’m fairly sure that the strict definition requires searing first and then cooking in liquid, which doesn’t happen here, and so maybe this is more of a stewing. But that doesn’t sound as nice unless you’re English, which sadly I am not.
The benefits are a silky, yielding tuber in a rich sauce thickened by the natural starch in the flesh, and almost no active time required of the cook, as the stove does the bulk of the work.