The white path refers to the orbit of the moon around the earth, also called the Milky Way.
White holes are just something deduced from the general theory of relativity and are the opposite objects of black holes. It's like a quadratic equation with two solutions, equal in value and opposite in sign. One of the solutions corresponds to a black hole, but what about the other solution? In engineering, it is usually discarded, but physicists don't think so. They think this unreasonable solution may also have practical significance, so they imagined something with properties completely opposite to those of a black hole, and named it a "white hole."
However, this kind of thing has never been proven to actually exist.