What is the next week?

next week means the week starting on the coming Sunday since calendars start new weeks on Sunday.

What day is the start of next week?

Monday is the first day of the week according to the international standard ISO 8601, but in the US, Canada, and Japan, it’s counted as the second day of the week. Monday is named after the Moon. Monday comes after Sunday and before Tuesday in our modern-day Gregorian Calendar.