The __call__() method in Python is a special method that allows an object to be callable like a function. When the __call__() method is defined inside a class, instances of that class can be called as if they were functions.

Here is an example to illustrate the usage of __call__() method:

class Foo:  
    def __init__(self):  
        self.counter = 0  
    def __call__(self):  
        self.counter += 1  
        print(f"Instance called {self.counter} times")  
foo = Foo()  
foo()  # This will print: "Instance called 1 times"  
foo()  # This will print: "Instance called 2 times"  

In this example, the Foo class has a __call__() method defined. The method increments the counter attribute each time it is called and prints the value of counter. Instances of the Foo class can be called as if they were functions, and each call will increment the counter attribute and print the updated value.

The __call__() method can also accept arguments and return a value, just like regular functions.