Uniform laws are pieces of legislation that are created by non-government entities and submitted to state legislatures for approval.
The purpose of uniform laws is to try to create uniformity in legislature across multiple or all states when it makes good sense to do so. Sometimes, these laws are approved by states and sometimes not.
The National Conference of Commissioners on Uniform State Laws is the organization that is responsible for creating uniform laws.
The benefit of uniform laws is that they can create identical standards, regulations, codes, etc. that can be used in an identical fashion in every state that accepts them. This can make things such as conducting interstate business significantly easier. This is because all the companies involved can know in advance what is expected in terms of laws that govern the industry.