What’s wrong with the tree? What’s the name of the tree? How should I treat it? Or simply do nothing?
Certified GKH Gardening Expert
It appears to be a Plumeria with bacterial spotting!
A fungicide will be in order. Here is an article that will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
It will be best to hold off on watering until the soil is completely dry down to about 3 inches or so between watering. Overwatering is the most common cause of what you are seeing here.
Make sure to trim off any leaves that are affected, then completely remove them from the area as to avoid spreading the disease.
Here is an article that will help you with their care: https://www.gardeningknowhow.com/ornamental/flowers/plumeria/growing-plumeria.htm