What is the use of numpy.random.seed() Does it make any difference?

I have a dataset named "admissions".

I am trying to carry out holdout validation on a simple dataset. In order to carry out permutation on the index of the dataset, I use the following command:

import numpy as np
np.random.permutation(admissions.index)

Do I need to use np.random.seed() before the permutation? If so, then why and what does the number in np.random.seed(number)represent?