This is a permanent visa which allows Australian businesses to nominate a skilled worker to stay in Australia and work in their business. It is comprised of two steps, the first is the nomination, and the second is the visa application.
Workers who hold a s/c 457 (or certain TSS visa holders) may be able to use this to transition from their temporary visa, into a permanent visa!
There are three streams, the main being the direct and 457/TSS holder pathways. You only have to meet one set of criteria.