Box 5 is taxable income from the estate, not a straight inheritance. But it's a catch-all for income that didn't fit into any of the other boxes. You will have to ask the executor of the estate, or the tax person who prepared the estate income tax return, what the income is from and why it's taxable.
The negative amount with code H in box 14 is an adjustment that excludes the income from the estate from the additional 3.8% Net Investment Income Tax. But the income is still subject to regular income tax.
I will ask a couple of other SuperUsers if they can give you any better explanation, but I think you are going to have to ask the executor, as I said.
