Assuming they are reading it from the floor of the House (or Senate), it does protect them from being prosecuted: "and for any Speech or Debate in either House

Assuming they are reading it from the floor of the House (or Senate), it does protect them from being prosecuted: "and for any Speech or Debate in either House, they shall not be questioned in any other Place." They would be subject to whatever punishments their fellow Representatives (or Senators) decided to impose (including possibly expulsion).