Homestead exemption is a reduction in the assessed valuation of the real estate you use as your main home (which results in an overall lower real estate tax bill). The exemption is not entered anywhere on your federal income tax return, it will automatically be reflected in the documentation you receive from your state.
To check on your Homestead exemption, you will need to check with your county courthouse, at the tax assessor's office. In most states you can check this online.