What right does the principle of patent application first embody in intellectual property rights?

Priority.

The principle of prior application of intellectual property rights mainly refers to patent rights, which does not apply to copyright. Most countries in the world (except the United States, which implements the principle that whoever invents first enjoys the right) apply for a patent first, that is, whoever applies for the same technological invention first gets it first. This principle gives priority to time, so inventors are required to have a strong awareness of intellectual property protection.