How can I plot line plots based on an input python dataframe?
Here's a solution:

I've created a sample dataframe with some arbitrary values. Here it is:

import pandas as pd
import numpy as np
from datetime import datetime

test = pd.read_csv('/home/sagar/Desktop/test.csv')
# Convert your date from 'str' to 'datetime' format
test['SUMRY_DT'] = test['SUMRY_DT'].map(lambda x: datetime.strptime(x, '%Y-%m-%d'))
# Set it as your dataframe index
test.set_index('SUMRY_DT', inplace=True)
test
            CMPGN_NM                    COST_SUM
SUMRY_DT        
2018-05-17  GSA_SMB_SMB_Generic_BMM     8985
2018-05-18  GSA_SMB_SMB_Generic_BMM     7456
2018-05-19  GSA_SMB_SMB_Generic_BMM     5761
2018-05-20  GSA_SMB_SMB_Generic_BMM     4251
2018-05-21  GSA_SMB_SMB_Generic_BMM     10521
2018-05-22  GSA_SMB_SMB_Generic_BMM     10216
2018-05-23  GSA_SMB_SMB_Generic_BMM     11023
2018-05-24  GSA_SMB_SMB_Spark           11242
2018-05-25  GSA_SMB_SMB_Generic_BMM     8817
2018-05-26  GSA_SMB_SMB_Generic_BMM     6937
2018-05-27  GSA_SMB_SMB_Generic_BMM     4581
2018-05-10  GSA_SMB_SMB_Spark           7089
2018-05-13  GSA_SMB_SMB_Spark           2121
2018-05-11  GSA_SMB_SMB_Spark           234
2018-05-12  GSA_SMB_SMB_Spark           11077

# Plot your data
test.groupby('CMPGN_NM')['COST_SUM'].plot(legend=True)




With the actual data, your chart would resemble the picture you have provided.

Hope this helps.