How to call 3rd party plugin's filter and assign it to a shortcode

Question

I'm pretty new to the whole WordPress world so I could need some help. I have a 3rd party plugin that provides a bunch of actions, filters, and functions. How can I call them in my functions.php file and assign a shortcode to it, so I can use it on a single page template in this case?

Here is an example:

That's what I tried so far, but it doesn't do anything on the front-end:

function wpc_elementor_shortcode( $atts ) {
    echo apply_filters( 'sensei_lesson_count', $post_args );
}
add_shortcode( 'my_elementor_php_output', 'wpc_elementor_shortcode');