ballistic shield
Ballistic Shields (also known as tactical shields or bulletproof shields) are modern day shields used by soldiers and heavily armed police officers. They're designed to stop bullets, protecting the wielder and others behind them from gunfire.
Not to be confused with riot shields which are usually made from lighter/cheaper materials, like transparent plastics, and are meant to block rioters, thrown objects, improvised weapons, and sometimes even small arms fire though aspects of both can overlap with one another.