If you are entering a continuing LLC S-Corp into TurboTax , then you will need to enter your 2016 Year-End balance sheet from the tax return into the software. Sometimes, a balance sheet is not required, and the software will not have included or printed it. If you want to include one anyway, then you can enter one from your record-keeping software (e.g. Quickbooks).
If 2017 is your first year, then the beginning balance sheet is all zeroes.