TypeError: Missing 1 required positional argument: 'self'

Works and is simpler than every other solution I see here :

Pump().getPumps()

This is great if you don't need to reuse a class instance. Tested on Python 3.7.3.

You need to instantiate a class instance here.

Use

p = Pump()
p.getPumps()

Small example -

>>> class TestClass:
        def __init__(self):
            print("in init")
        def testFunc(self):
            print("in Test Func")


>>> testInstance = TestClass()
in init
>>> testInstance.testFunc()
in Test Func

The self keyword in Python is analogous to this keyword in C++ / Java / C#.

In Python 2 it is done implicitly by the compiler (yes Python does compilation internally). It's just that in Python 3 you need to mention it explicitly in the constructor and member functions. example:

class Pump():
    # member variable
    # account_holder
    # balance_amount

    # constructor
    def __init__(self,ah,bal):
        self.account_holder = ah
        self.balance_amount = bal

    def getPumps(self):
        print("The details of your account are:"+self.account_number + self.balance_amount)

# object = class(*passing values to constructor*)
p = Pump("Tahir",12000)
p.getPumps()

You need to initialize it first:

p = Pump().getPumps()