The tree took a lighting strike
Ah, well that's kind of important info there.
If the lightning's path to ground stayed to the outside, then just the bark in that area will fall off, and the branches at the top where the lightning entered will die. You can treat teh tree with the sick tree treatment to boost its health, and that should take care of it. A tree can survive that kind of strike.
If the lightning path to ground went through the centre of the tree, then it's a goner.
The fact that the bark appears to only be coming off one side is hopeful that it was a surface path rather than the core.