import pandas as pd

# Creating a DataFrame
df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]})

# Renaming all columns
df.columns = ['NewA', 'NewB']

# Print data frame
print(df)

>>>

    NewA  NewB
0     1     4
1     2     5
2     3     6