13th month pay is a bonus given to employees in addition to their regular salary, typically at the end of the year. The bonus is usually equivalent to one month's salary and is intended to help employees with their year-end expenses. The practice of providing a 13th month pay is common in some countries like Philippines, it is required by law for employers to provide this bonus to their employees. It's not a common practice in all countries, but some companies may still choose to provide it as a benefit to their employees.