Why is there an amount in "Excess Real Estate Taxes" from last year that equals the amount I paid in Insurance?

I just did my 2018 taxes in October, and I remember coming to this part in the Home Office section, and thinking that I had mistakenly entered my insurance twice. Why does TT have that number in there? And, I paid $3316 in real estate taxes, so it seems that I should have zero excess real estate taxes, right?