Q:

how to implement the switch case in python..?

Check this below code:
var = input("enter a number between 1 and 12")
def switch_demo(var):
    switcher = {
                1: "Jan" 
                2: "Feb" 
                3: "March"
                4: "April" 
                5: "May" 
                6: "June" 
                7: "July" 
                8: "August" 
                9: "Sept" 
                10: "Oct" 
                11: "Nov" 
                12: "Dec"
    }
    print switcher.get(var,"Invalid Month")

I am getting Syntax Error at line 5
How can I solve the error?

A:

Fixing your Bugs
You need to add a comma at the end of each item:
 1: "Jan", 
 2: "Feb",

Working program:
def switch_demo(var):
    switcher = {
                1: "Jan", 
                2: "Feb", 
                3: "March",
                4: "April", 
                5: "May", 
                6: "June", 
                7: "July", 
                8: "August", 
                9: "Sept", 
                10: "Oct", 
                11: "Nov", 
                12: "Dec"
    }

    return switcher.get(var,"Invalid Month")

var = int(input("enter a number between 1 and 12"))
print(switch_demo(var))

Simpler Solution
You should have a look at the  calendar module.
It already provides all months names:
>>> import calendar
>>> calendar.month_name[3]
'March' 

