Picture via https://onlinebicyclemuseum.co.uk/1930s-lever-driven-bicycle/ and it has a nice story to it if you care for it. The last quote is very dudes rock. Also this has iron tyres on wooden wheels.
This is a singlespeed. Much like there is more than one way to skin a cat, there is more than one way to convert leg movement into rotational force to go well far on two triangles. Like you could just plonk some levers on the rear and use those to convert some leg motion into going forward via wheel. This, by description, would have had freewheels of some sort, but conceptually you could make this even more low tech as a fixie, one lever fixed at the top, one at the rear of the wheel, off you go.
going by the description on the website I think you'd just do the very odd pedal motion backwards to brake. sort of like a coaster brake but not really. But also it's iron rimmed wooden wheels, pretty sure "just stop pedaling" slows you down pretty fast