The % symbol means the "modulo" operator in JavaScript. This operator returns the remainder after division is applied. So here it would return the remainder of whatever Date().getTime() returned. For example, if the function returned a value of 23, the % would take the remainder of 23/5, which is 3.

% sign simply returns the remainder for example 11%5 will return 1 as the answer.Hope you got your answer

% in the programming world means mod which is the remainder of a division. for instance, 11 divided by 5 equals 2 and the remainder is 1. Here are some resources that teach mod in-depth:

MDN Docs

Geekbox

Better Explained

Stackoverflow

That is being said in the code you've provided you are creating a new date object and extracting the time out of it. So basically this code is trying to select a carad class with the remainder of the date. I have attached a code snippet that will help you understand the idea more.

$(function() {
   $(".carad" + new Date().getTime() % 5).css("color", "red");
   $(".display-mod").text("the remainder is " + new Date().getTime() % 5);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<h1 class="carad0">Hello world 0</h1>
<h1 class="carad1">Hello world 1</h1>
<h1 class="carad2">Hello world 2</h1>
<h1 class="carad3">Hello world 3</h1>
<h1 class="carad4">Hello world 4</h1>
<h1 class="carad5">Hello world 5</h1>
<h1 class="carad6">Hello world 6</h1>

<p class="display-mod"></p>

In short, this code selects a class with a random number.

Note: I've changed the applied styles to emphasize the idea