What are brake clamps?

Brake blocks are the brake pads on a rim brake on the bike.

Brakeӧtze:
Part of the rim brake. By pressing the brake lever, i.e. pulling on the brake cable, they are pressed onto the rim and slow down the journey, as the wheels are slowing down in their rotation.

Relevant contributions:
Bicycle safety tips, 
Spring check, 
Road -proof bike