You may have recently received a completed Form 1095-B like the one shown in this article from CommunityCare. This is because the Affordable Care Act (ACA) created various new reporting requirements for employers and insurance carriers. Your insurance carrier and/or your employer were required to issue the new reports by March 31, 2016.
Form 1095-B verifies for the IRS and your tax preparer the months during 2015 that you had qualifying health insurance coverage. Therefore, it will help determine whether or not you owe a tax penalty for not having qualifying coverage. You do not need to attach Form 1095-B to your tax return - be sure to save it for your tax records.