Your tree looks like an ornamental fruit tree.

The green splotches along the trunk are called lichens, and they are totally harmless to the tree. Here is our page about them: 

https://extension.umd.edu/resource/algae-and-mosses

Of greater concern is the large sunken area on the right limb side of the photo, which look like it could have been where a wound or branch broke off in the past. It looks like the tree has produced some callous tissue around the edges trying to heal itself but has been unable to close the area. That will end up being a weak area prone to rot and stability challenges.

Ornamental fruit trees, particularly plums, tend to only have a useful life of about 20 years or so before they start to decline, so enjoy it while it is attractive. Prune out any dead branches and offer it water in times of drought or when we don't get at least an inch of rain a week.

The leaf eating is minor and we wouldn't be concerned about it.

Did it bloom this spring? If it did not it could be stress related. If it did, it's possible the reasons for no fruit could be incomplete pollination or the killing of the pollen/blossom by late frosts.

Christine

If it would fall on anything valuable, including other plants, then that is time to remove it.  But it looks healthy and should have some years in it.  The wound seems to have healed well.

Here's a page on when to remove trees: https://extension.umd.edu/resource/how-do-you-decide-when-remove-tree

We always recommend replacing with a native tree.  A landscape with at least 50% native plants is a good goal for everyone. 

Ellen