Is it possible to shorten my if/else statement?

The Questions of if/else statements and other alike codes

Hi, currently I am using this code to call an if/else statement, to add and/or remove the class ".hide" whenever the different tables are clicked on. This code is working all fine, no trouble with it at all.

Example 1

$(document).ready(function() {
    $('#Year_Table').click(function() {
        if ($('#Month_Table').hasClass("hide")) {
            $('#Month_Table').removeClass('hide');
        } else {
            $('#Month_Table').addClass('hide');
            $('#Day_Table').addClass('hide');
        }
    });
});

But what I am wondering about, is if there is anyway to make the code shorter? but with the same outcome. That the class is add or removed.

I had another question a few days ago, where a guy shortened my if/else statement to this code below. Thank you

Example 2

$( document ).ready(function(){
    var games_month  = 0;
    var month_games  = "Games";

    $("#Games_Month").html(games_month);

    $('#January').click(function(){ 
        $('#Games_Month').html(function(_, html) {
        return html === month_games ? games_month : month_games;
     });
});

The shortened code works perfectly too, but gives me a couple of question marks. Now, what I would like to know is:

1: What is this type of code that was shortened for me? I mean, what is it called?

I have been told it might be a callback function.

2: What is different from a standard if/else statement and the shortened code?

is it the same, just cleaned up? or is there any important difference?

3: What does the different parts of the shortened code mean? what do they do?

To me it just seem like another kind of an if/else statement?

4: is there any way to make such a code with classes instead of variables?

Simply instead of changing the variable, I would like to add or remove the class ".hide" and is it possible to add and remove several classes within this function?

5: Is there any other ways to code an if/else statement or code which gives the same result?

I am very new at using both javascript and jQuery, but I'm trying to learn as much as possible. I appreciate all the help I can get to understand all this, everything will help me getting further into my knowlegde of coding.

Thank you very much.