Property tax is not technically a box of your 1098. However, many lenders provide the information somewhere on the 1098 paper as a courtesy. The 1098 boxes are only about your mortgage. Its not about monies you pay to your town or home insurance provider.
So, its not in one of the 1098 boxes, but you should see your escrow info along the page somewhere. (Perhaps in the bottom left right below the 1098.) You might see your home insurance too. It shouldn't be difficult to locate. It should use the words "real estate taxes" or "property taxes disbursed".
You may also have a separate escrow statement for this, that isn't on the 1098 "page"