Yes, this is where you enter your HSA contributions that were made independently (not through payroll).
If your employer doesn't offer payroll deductions to your HSA, you can continue to do this yourself. However, if it is possible to contribute to your HSA through payroll, you will save on FICA taxes (7.65%), which can be a significant savings over time.
Here's an article about HSAs: Basics of Health Savings Accounts
