A fortnight is 14 days or 2 weeks in length.
There are zero weeks in a forthnight because forthnight is not a real word! There are 2 weeks in a FORTNIGHT.
Two weeks.
Nope! It appears to be a misspelling of "Fortnight."
It is a period of time lasting 2 weeks in duration.
A fortnight is a period of two weeks, typically used in British English. It is a convenient way to describe a span of time that equals 14 days.