What does this rg.random mean?

Here's the docs from numpy: https://numpy.org/devdocs/user/quickstart.html#changing-the-shape-of-an-array

And you can see in the first line of code:

a = np.floor(10*rg.random((3,4)))

np stands for numpy - but rg? Surprisingly I also couldn't find anything on google...

I should also say that the output of that code is 3 rows with 4 columns with random numbers inside of that array. Thanks