Not to be too picky... but it's a probably a best before date, not expiry. Salt itself has no expiration date though of course, but salt products that contain iodine can deteriorate over time, different moisture content etc.
The shelf life of salt depends on its type and how it’s stored. Generally speaking, regular table salt has an indefinite shelf life, meaning it won’t expire but its minerals may break down over time. This is because salt is a very stable mineral with very low water content, making it difficult for bacteria to grow.
That said, when using salt in food, it should be noted that its flavor may not be as pronounced after a while. In terms of food safety, unopened packages of table salt can be stored indefinitely, while opened packages should be discarded after two to three years.
When it comes to the other types of salts mentioned above, they may have shorter shelf lives due to their higher moisture content. Sea salt and kosher salt are more prone to clumping over time due to their higher mineral content, so these types should be discarded one to two years after opening. As for Himalayan pink salt, its shelf life will depend on how it’s stored; unopened packages can typically last up to five years, while opened packages should be discarded within a year or two.