Optional Lab_Gradient Descent

I have just completed the week 1 of Supervised Learning
I didn’t understand this part of code in the optional lab , what is num_iters ?
why for i in range(num_ iters) is used ?
and everything below from for loop .
I do understand the code which is above this like compute_cost and compute_gradient

The num_iters is the number of iterations. If you don’t understand the code then it’s better to leave the course now and learn the basics of Python. Then come back to the course. This specialization assumes that you are familiar with Python. But just learn the basics, don’t need to become an expert in Python.