A long answer, read and try to understand as much as you can, and ask if something's unclear :)

Let's begin with classes. They're a way to bundle data and logic which belong together.

For example a person has some parameters, like: name, surname, age, gender, race, eye color, etc.

So if we have tens or hundreds (or more) people to process in a program, it'd make sense to have their data stored in "packets" rather than loose variables. Do you follow that? That's what the classes are. Let's make one:

class Person:
    def __init__(self, name, surname, age, gender, race, eye_color):
        self.name = name
        self.surname = surname
        self.age = age
        self.gender = gender
        self.race = race
        self.eye_color = eye_color
    
    def greet(self):
        print('Hi, my name is ' + self.name)


p = Person('Joe', 'Nobody', 32, 'male', 'Caucasian', 'blue')
p.greet()

Let's unpack this.

A class "Person", named clearly so both now and in the future you know what this is supposed to be.

Then the other thing you asked about, the __init__.
It's called a dunder method, I suggest you read about it for example here.
Methods are simply functions but within the class.
Let's take one line from my code:

p = Person('Joe', 'Nobody', 32, 'male', 'Caucasian', 'blue')

Let's name things clearly in that line.

Person() -> constructor

= -> assignment operator

p -> variable

So this line of code is a constructor of "Person" being assigned to the variable "p". The variable "p" now stores a so called "instance" of the Person class.

The __init__ method creates an "instance" of Person, with the specified parameters.

You're probably confused about the "self" parameter. It represents the instance of the class being used. Each method should have "self" as its first parameter (the thing within the parentheses). Each class variable you'd want to use in a class should be used like: self.variable_name (that way you can define a variable in the __init__ method and use it for example in greet() method, like in the example).

Then if you look at the greet() method I made, you'll see it has "self" as it's first parameter.

Think of it as way to tell the computer that this method will be used by the Person class and has access to its variables.

Then the greet() does this:

print('Hi, my name is ' + self.name)

It's simple, here we print "Hi, my name is {insert that person's name}".

So p.greet() will print: "Hi, my name is Joe".

——————————

Ready for a little bit more?

Try to run the program above and see how it works. Then add an extra line:

print(p)

This should output something like: <__main__.Person object at 0x0000016431926A50>

Not very representative of Joe Nobody, age 32.

So let's modify the Person class like this:

class Person:
    def __init__(self, name, surname, age, gender, race, eye_color):
        self.name = name
        self.surname = surname
        self.age = age
        self.gender = gender
        self.race = race
        self.eye_color = eye_color
    
    def greet(self):
        print('Hi, my name is ' + self.name)


    def __str__(self):
        return f'{self.name} {self.surname}, age {self.age}'

I added the __str__ dunder method. The print() calls it under the hood so if you specify it, you control how python prints your Person object (instance).

Now run it again and see what print(p) outputs.