I really wonder, the following sentences relate to each other? Why can we emphasize about in a sentence?
The restaurant closes in about 5 minutes.
The restaurant closes in 5 minutes.
In the first sentence, about conveys that the amount of time is approximate. From Collins:
approximately; near in number, time, degree, etc ⇒ "about 50 years old"
In the second sentence, there is no such indication. The number may be exact, but it may also be an approximation.
If you want to make it clear that it's not an approximation, you can indicate that it's an exact number by saying "exactly five minutes", "five minutes flat", "five minutes and zero seconds", or something similar.