Saint Ruth is not a patron saint of any specific thing, but was declared a saint posthumously by the Roman Catholic Church. Saint Ruth is a biblical figure that is prominent in Judaism, Christianity and Islam.
Catholicism has many patron saints, such as Stephen, the patron saint of deacons, but not all saints have a specific patronage that is part of their namesake. Most saints were granted their sainthood centuries after their deaths because of their actions and devotion to God in life. A saint is defined as "one who has been recognized for having an exceptional degree of holiness."