I assume you are familiar with what CPU architecture is. The famous one is x86 and ARM. This is just another one of those called RISC-V.
The significance is mostly political. US and allies have been trying to sanction China technologically. They even tried to block export of RISC-V, but since it is open source, they can just get fucked. Now, China can only get sub par GPU and limited CPU. Pushing for RISC-V means China is aiming to further develop it to be as capable as the CPU being sanctioned effectively making the sanction useless and even furthering Chinese manufacturing capabilities in the process.
The big advantage is that this is technically more standardized and free. Unlike ARM which require license, RISC-V doesn't so anyone can make their own CPU and get the software support already in place. Hopefully more CPU manufacturers will be created from the advancement of RISC-V making more fierce competition.