Firstly, since the file you have is a csv file, I would recommend using the built-in csv module in python to parse it as it will make it a lot easier.
Code:
import csv

def show_reservation(file_path):
    # Using a list of tuples as I'm assuming we can have multiple reservations for the same time
    reservation_info = []
    # Use a context manager here so that you don't 
    # have to remember
...