how to get the number of values in a column pandas code example

Example 1: pandas dataframe get number of columns

import pandas as pd
df = pd.DataFrame({"pear": [1,2,3], "apple": [2,3,4], "orange": [3,4,5]})

len(df.columns)
3

Example 2: pandas count values by column

df = pd.DataFrame({'a':list('abssbab')})
df.groupby('a').count()