AttributeError: 'numpy.ndarray' object has no attribute 'value_counts'

# Counting values from a numpy array

import numpy as np

a = np.array([0, 3, 0, 1, 0, 1, 2, 1, 0, 0, 0, 0, 1, 3, 4])
unique, counts = np.unique(a, return_counts=True)
dict(zip(unique, counts))

output: {0: 7, 1: 4, 2: 1, 3: 2, 4: 1}


# Counting values from a pandas dataframe

import pandas as pd

let's suppose there's a dataframe as follows:
a = np.array([0, 3, 0, 1, 0, 1, 2, 1, 0, 0, 0, 0, 1, 3, 4])
a = pd.DataFrame(a)
print(a.value_counts())