I am unable to understand parts of the code

#!/usr/bin/python3
# File name   : motor.py
# Description : Control Motors 
# Website     : www.adeept.com
# E-mail      : support@adeept.com
# Author      : William
# Date        : 2018/10/12

import RPi.GPIO as GPIO
import time
# motor_EN_A: Pin7  |  motor_EN_B: Pin11
# motor_A:  Pin8,Pin10    |  motor_B: Pin13,Pin12

Motor_A_EN    = 4
Motor_B_EN    = 17

Motor_A_Pin1  = 14
Motor_A_Pin2  = 15
Motor_B_Pin1  = 27
Motor_B_Pin2  = 18

Dir_forward   = 0
Dir_backward  = 1

pwm_A = 0
pwm_B = 0

def setup():#Motor initialization
    global pwm_A, pwm_B
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(Motor_A_EN, GPIO.OUT)
    GPIO.setup(Motor_B_EN, GPIO.OUT)
    GPIO.setup(Motor_A_Pin1, GPIO.OUT)
    GPIO.setup(Motor_A_Pin2, GPIO.OUT)
    GPIO.setup(Motor_B_Pin1, GPIO.OUT)
    GPIO.setup(Motor_B_Pin2, GPIO.OUT)
    try:
        pwm_A = GPIO.PWM(Motor_A_EN, 1000)
        pwm_B = GPIO.PWM(Motor_B_EN, 1000)
    except:
        pass

def motorStop():#Motor stops
    GPIO.output(Motor_A_Pin1, GPIO.LOW)
    GPIO.output(Motor_A_Pin2, GPIO.LOW)
    GPIO.output(Motor_B_Pin1, GPIO.LOW)
    GPIO.output(Motor_B_Pin2, GPIO.LOW)
    GPIO.output(Motor_A_EN, GPIO.LOW)
    GPIO.output(Motor_B_EN, GPIO.LOW)

def motor_right(status, direction, speed):#Motor 2 positive and negative rotation
    global  pwm_B
    if status == 0: # stop
        motorStop()
    else:
        if direction == Dir_forward:
            GPIO.output(Motor_B_Pin1, GPIO.HIGH)
            GPIO.output(Motor_B_Pin2, GPIO.LOW)
            pwm_B.start(100)
            pwm_B.ChangeDutyCycle(speed)
        elif direction == Dir_backward:
            GPIO.output(Motor_B_Pin1, GPIO.LOW)
            GPIO.output(Motor_B_Pin2, GPIO.HIGH)
            pwm_B.start(0)
            pwm_B.ChangeDutyCycle(speed)

def motor_left(status, direction, speed):#Motor 1 positive and negative rotation
    global pwm_A
    if status == 0: # stop
        motorStop()
    else:
        if direction == Dir_forward:#
            GPIO.output(Motor_A_Pin1, GPIO.HIGH)
            GPIO.output(Motor_A_Pin2, GPIO.LOW)
            pwm_A.start(100)
            pwm_A.ChangeDutyCycle(speed)
        elif direction == Dir_backward:
            GPIO.output(Motor_A_Pin1, GPIO.LOW)
            GPIO.output(Motor_A_Pin2, GPIO.HIGH)
            pwm_A.start(0)
            pwm_A.ChangeDutyCycle(speed)
    return direction


def destroy():
    motorStop()
    GPIO.cleanup()             # Release resource


try:
    pass
except KeyboardInterrupt:
    destroy()

Here is the link to the entire project, please check this:

What is the meaning of the lines :

• pwm_A = GPIO.PWM(Motor_A_EN, 1000)
• pwm_B = GPIO.PWM(Motor_B_EN, 1000)

      def motor_left(status, direction, speed):#Motor 1 positive and negative rotation
          global pwm_A
          if status == 0: # stop
              motorStop()
          else:
              if direction == Dir_forward:#
                  GPIO.output(Motor_A_Pin1, GPIO.HIGH)
                  GPIO.output(Motor_A_Pin2, GPIO.LOW)
                  pwm_A.start(100)
                  pwm_A.ChangeDutyCycle(speed)
              elif direction == Dir_backward:
                  GPIO.output(Motor_A_Pin1, GPIO.LOW)
                  GPIO.output(Motor_A_Pin2, GPIO.HIGH)
                  pwm_A.start(0)
                  pwm_A.ChangeDutyCycle(speed)
          return direction

What is the meaning of status, direction, speed in the function declaration?

Also pwm.changeDutyCycle(speed), What is the speed?