Hide div after a few seconds

This will hide the div after 1 second (1000 milliseconds).

setTimeout(function() {
    $('#mydiv').fadeOut('fast');
}, 1000); // <-- time in milliseconds

#mydiv{
    width: 100px;
    height: 100px;
    background: #000;
    color: #fff;
    text-align: center;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="mydiv">myDiv</div>

If you just want to hide without fading, use hide().

You can try the .delay()

$(".formSentMsg").delay(3200).fadeOut(300);

call the div set the delay time in milliseconds and set the property you want to change, in this case I used .fadeOut() so it could be animated, but you can use .hide() as well.

http://api.jquery.com/delay/

jquery offers a variety of methods to hide the div in a timed manner that do not require setting up and later clearing or resetting interval timers or other event handlers. Here are a few examples.

Pure hide, one second delay

// hide in one second
$('#mydiv').delay(1000).hide(0); 

Pure hide, no delay

// hide immediately
$('#mydiv').delay(0).hide(0); 

Animated hide

// start hide in one second, take 1/2 second for animated hide effect
$('#mydiv').delay(1000).hide(500); 

fade out

// start fade out in one second, take 300ms to fade
$('#mydiv').delay(1000).fadeOut(300); 

Additionally, the methods can take a queue name or function as a second parameter (depending on method). Documentation for all the calls above and other related calls can be found here: https://api.jquery.com/category/effects/