Salt, or sodium chloride, is a non-renewable resource. A resource is defined as renewable only if it is self-replenishing. While new salt is being formed by natural processes in the earth, the timescale for that formation is too vast for salt to be considered self-replenishing in terms of human use.
Most of the world's salt supply is dissolved in seawater. When seawater evaporates, a crust of salt is left behind. This is not new salt, it has just precipitated out of solution. While salt is technically a non-renewable resource, it is also one of Earth's most abundant minerals, and there is little danger of humans ever running out.