The True Lunar Nodes are the Lunar Nodes but calculated with the slight fluctuation of those points taken into account, as opposed to averaging their position.
The Lunar Nodes are the two places where the orbit of the Moon around the Earth intersects with the (apparent) path of the Sun around the Earth (from our perspective on Earth). The positions of these nodes are always opposite and move in an overall retrograde direction.
The precise position of the nodes actually fluctuate slightly due to a wobble in the gravitational centre between the Earth and Moon. As a result, the True Nodes oscillate back and forth slightly. Like the Mean Nodes, the True Nodes are retrograde most of the time. The oscillation factor causes the True Nodes to switch to a direct motion briefly, lasting hours to days, and then resume their normal retrograde motion.
The True Nodes are interpreted the same way as the Mean Nodes; they're just calculated differently.