What is BHEEM, Shubhanshu Shukla's concept for building homes on Mars & Moon?

Indian astronaut Shubhanshu Shukla unveiled Bharatiya Extraterrestrial Expandable Modular Habitat (BHEEM) as a concept for a modular, panel-based habitat on the Moon and Mars that can be stacked inside rockets. BHEEM's panels can be joined together to form pressurised modules for astronauts. A single Starship could deliver panels to build a habitat twice the size of International Space Station.