Try converting string into date using the format of your date using pd.to_datetime()
use np.busday_count
to find difference between days excluding the weekends
import pandas as pd
import numpy as np
date1 = "01/07/2019"
date2 = "08/07/2019"
date1 = pd.to_datetime(date1,format="%d/%m/%Y").date()
date2 = pd.to_datetime(date2,format="%d/%m/%Y").date()
days = np.busday_count( date1 , date2)
print(days)
5
incase you want to provide holidays
holidays = pd.to_datetime("04/07/2019",format="%d/%m/%Y").date()
days = np.busday_count( start, end,holidays=[holidays] )
print(days)
4