dm

df.rename(columns={
    'step':'Step',
    'type':'Type',
    'amount':'Amount',
    'nameOrig':'sender name',
    'oldbalanceOrg': 'sender old balance',
    'newbalanceOrig': 'sender new balance',
    'nameDest':'client',
    'oldbalanceDest': 'client old balance',
    'newbalanceDest': 'client new balance',
    'isFraud':'Fraudulent',
    'isFlaggedFraud':'Flagged as Fraudulent'
}, inplace= True)
df