Article 24 of the Universal Declaration of Human Rights grants every human the right to leisure and rest. And rightly so, because toil and inhuman working conditions make it impossible to enjoy any other human right or any meaningful human activity. One way to guarantee a reasonable measure of leisure is to limit the number of hours worked per day. Another way is to grant people a certain number of paid holidays (see also article 24). Here’s an international comparison of rich countries (poor countries, of course, have other priorities).
(The U.S. has 0 days because there’s no legislation on vacation, which doesn’t mean Americans have no holidays).