What is the interpretation of the noble verse "رب المشرقين ورب المغربين"? And does it indicate the existence of another world?

The Quran mentions the East and the West in different forms (singular, dual, plural), and there is no contradiction between them. The singular form refers to the general category of the East and the West. The dual form refers to the two Easts and the two Wests of summer and winter. As for the plural form, it refers to the varying rising and setting points of the sun each day throughout the year, or to the Easts and Wests of different regions on Earth, or even on other planets. This multiplicity reflects the scientific miraculousness of the Quran, as the places of sunrise and sunset change daily.