Can you tell me please how much time premier pro should take in exporting a 5 mins video?

There is no one answer to this as there are so many variables.

The best short answer is: it takes as long as it takes.

Nope, sorry. That depends on a long list of things:

1) How powerful your hardware is

2) What format your source footage is

3) What format and quality settings you're exporting to

4) How many effects you have

     a) whether those effects are GPU-accelerated or not

5) Whether or not you're using GPU acceleration upon export

6) What kind of drive your source footage is on (speed of drive)

7) What kind of drive you're exporting to