As to what that is, is hard to tell. But I'd be gettin' that out of there before it grows up into a large, seeding-out type grass if I were you...

Also, I think your Bermuda needs feeding. Even in the closeup, it has a hungry sort of look about it, and seems a bit thin and reedy.

It looks more like a genetic mutation towards an all white variegated leaf of the Bermuda grass to me. Highly unlikely it will have more vigor than the plain green. This is one way plants get patented, finding something completely new that can be propagated and stay true to the new form.

I would dig it up, pot it up, make it happy and grow it out to see what it will do. It could be worth something. I can totally see an all white lawnette in the right garden. I had a nice white variegated St. Augustine lawn for a spell. It was fab during a full moon.

What Christopher said.