Python Player Movement SIMPLIFIED with explanation

Beware that 19:19 to 25:12 is an error.

This video includes how to use pygame, the basics of pygame, python, and how to solve errors.
Final Code of the game:
import pygame,sys
WIDTH, HEIGHT = 350,350
TITLE = "Player Movement Smooth"

pygame.init()
win = pygame.display.set_mode((WIDTH,HEIGHT))
pygame.display.set_caption(TITLE)
clock = pygame.time.Clock()

class Player:
def __init__(self,x,y):
self.rect = pygame.Rect(x,y,32,32)
self.x = int(x)
self.y = int(y)
self.color = (250,120,60)
self.velX = 0
self.velY = 0
self.left_pressed = False
self.right_pressed = False
self.up_pressed = False
self.down_pressed = False
self.speed = 4

def draw(self,win):
pygame.draw.rect(win, self.color,self.rect)

def update(self):
self.velX = 0
self.velY = 0
if self.left_pressed and not self.right_pressed:
self.velX = -self.speed
if self.right_pressed and not self.left_pressed:
self.velX = self.speed
if self.up_pressed and not self.down_pressed:
self.velY = -self.speed
if self.down_pressed and not self.up_pressed:
self.velY = self.speed

self.x += self.velX
self.y += self.velY

self.rect = pygame.Rect(self.x,self.y,32,32)

player = Player(WIDTH/2,HEIGHT/2)

while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
sys.exit()

if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
player.left_pressed = True
if event.key == pygame.K_RIGHT:
player.right_pressed = True
if event.key == pygame.K_UP:
player.up_pressed = True
if event.key == pygame.K_DOWN:
player.down_pressed = True

if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT:
player.left_pressed = False
if event.key == pygame.K_RIGHT:
player.right_pressed = False
if event.key == pygame.K_UP:
player.up_pressed = False
if event.key == pygame.K_DOWN:
player.down_pressed = False

win.fill((12,24,36))
player.draw(win)

player.update()
pygame.display.flip()

clock.tick(120)

We do not tolerate with unfriendly or rude comments. This is a family-friendly channel.