what does pyplot do in python code example

Example 1: matplotlib.pyplot

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(0, 5, 0.1);
y = np.sin(x)
plt.plot(x, y)

Example 2: matplotlib.pyplot

plt.plot([1, 2, 3, 4], [1, 4, 9, 16]) # plot x against y