Keys.BACK_SPACE or Keys.TAB send key is not working on facebook selenium python

The issue here is that you are using misleading names for your methods.
You defined the following method

def actions():
    global actions
    actions = ActionChains(driver)

so that now when you calling actions.send_keys(Keys.BACK_SPACE) the interpreter thinks you are calling that actions method, not the actions object initiated inside it.
I would recommend you define this method as following

def set_actions():
    global actions
    actions = ActionChains(driver)

or even better not defining this method at all since this is not really method you are going to call several times.
The same about chrome_options and driver methods.
There is no need to define them as methods since these are not reusable methods, it could better be a flat code, so that the entire your code will look as following:

import os
import time
from selenium import webdriver
from selenium.webdriver.common.action_chains import ActionChains
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.keys import Keys

#Setting the chrome_options
global chrome_options
chrome_options = Options()
chrome_options.add_argument("--start-maximized")
chrome_options.add_argument('--profile-directory=Default')
# chrome_options.add_argument("--user-data-dir=chrome-data")
prefs = {"profile.default_content_setting_values.notifications": 2}
chrome_options.add_experimental_option("prefs", prefs)
chrome_options.add_argument('disable-infobars')
chrome_options.add_experimental_option("useAutomationExtension", False)
chrome_options.add_experimental_option("excludeSwitches", ["enable-automation"])

#Setting the Chrome Driver
global driver
driver = webdriver.Chrome("chromedriver.exe", chrome_options=chrome_options)

#Setting the Actions
global actions
actions = ActionChains(driver)


def login():
  driver.get("https://facebook.com")
    try:
        # I use environment variable  base on this tutorials https://www.youtube.com/watch?v=IolxqkL7cD8
        username = os.environ.get('my_facebook_username')
        password = os.environ.get('my_facebook_password')

        driver.find_element_by_name("email").send_keys(username)
        driver.find_element_by_name("pass").send_keys(password)
        driver.find_element_by_name("login").click()
        print(input("Press any Key: "))
        print("Login work Successfully ")

    except:
        pass


def navigatePagePostAria():
    sleepTime = 4
    implicitlyWaitTime = 20
    for i in range(2):
        driver.implicitly_wait(implicitlyWaitTime)
        actions.send_keys(Keys.BACK_SPACE)
        actions.send_keys(Keys.TAB * 4)
        time.sleep(sleepTime)
        actions.perform()
        print("Firast 10 tabs Working")

    actions.send_keys(Keys.TAB * 3)
    actions.send_keys(Keys.ENTER)
    actions.perform()
    print("Navigate Post area Successfully ")


login()
driver.get("https://www.facebook.com/groups/402353916617590/permalink/1630582000461436/")
navigatePagePostAria()

I also migrated the driver.get("https://facebook.com") into the login method since this belongs there more that to the basic initialization of the selenium webdriver itself