Understanding the concept ( Modules , imports )

[erfanakbari1]

Hey fellas .
I've been trying to learn bunch of stuffs about modules and imports in Python , meanwhile I was stopped because of some codes in which I can't quite get the actual concept behind it's mechanism & how it works .
This is the code

import time
from time import time as my_timer
import random

input("Please enter to start")

wait_time = random.randint(1, 6)
time.sleep(wait_time)
start_time = my_timer()
input("Press enter to stop")

end_time = my_timer()

print("Started at " + time.strftime("%X", time.localtime(start_time)))
print("Ended at " + time.strftime("%X", time.localtime(end_time)))

print("Your reaction time was {} seconds".format(end_time - start_time))

I really appreciate if someone could just explain line by line of this code and what is really does for us . Cause I don't have any problems with running the code . I just want to comprehend the lines of code .
Thanks