It is a Linux machine. Runs a Debian derivative, and it's not like Windows or anything else that isn't Linux/BSD can run on a RISC-V laptop.
This isn't the first RISC-V laptop, but the significance of a RISC-V laptop existing is primarily for developers who work on software targeting RISC-V systems. The ability to run RV64 programs without emulation and to natively compile RV64 software without cross-compilers is valuable to some people. Also, China in particular sees value in having computing products that aren't affected by sanctions; the processor in this is designed and manufactured by a Chinese company without licensing any intellectual property from US or UK.
Explaining what RISC-V is
RISC-V is a relatively newer CPU instruction set architecture that competes with x86 (Intel, AMD) and ARM (Qualcomm, Ampere, MediaTek, etc.). Its current designs don't really match those two in general-purpose performance yet but has the distinction of being a free, open, and extendable standard. Whereas x86 has only two CPU vendors and ARM has many vendors who all need to pay per-core license fees to ARM Holdings and have limits imposed on what they can do to it, RISC-V processors can be made by any hardware vendor with the means to make a processor and can be custom-designed to better fit specialized use-cases. Its use in general-purpose CPUs is catching on fastest in China but it sees use across the world in academia and in special-purpose processors by companies like Western Digital.