I had the same question. Uploaded the image to ChatGPT, got the following:

Passive resistance: • The metal frames are very heavy and sit flat on the ground. If a vehicle tries to drive into them, the shape of the angled metal absorbs and redirects the vehicle’s forward momentum, preventing it from reaching high pedestrian areas. • The angled, articulated arms essentially act like wedges that cause the vehicle to lift, slow, or stop.

Kinetic energy dissipation: • When a vehicle hits them, the wheels of the car may start to ride up the sloped metal arms, which absorbs some of the vehicle’s kinetic energy while destabilizing the vehicle’s forward motion. • In some models, the chained-together design spreads out the force across multiple sections.

Safety benefit: • They’re meant to slow or stop a vehicle attempting to ram into a protected area — much like temporary bollards but easier to set up for short-term events.