What is the WP_Internal_Pointers core class?

It implements the pointers feature, a UX change that was introduced in v3.3 to help point at new features when you first encounter them

You can use this yourself by enquing the wp-pointer script then using code similar to this:

jQuery(document).ready( function($) {
    $('#menu-appearance').pointer({
        content: '<h3>Edit The Appearance</h3><p>Edit the appearance of your WordPress theme.</p>',
        position: {
               edge: 'left',
               align: 'center'
           },
        close: function() {
            // Once the close button is hit
        }
    }).pointer('open');
});

WP_Internal_Pointers assists the WP Admin PHP in creating the admin pointers used by WordPress itself, however, it appears those pointers are no longer used. The functions that implement each pointer are empty, and the class is preserved for backwards compatibility.

While pointers still exist as a feature, they’ve fallen out of fashion in modern WordPress core development.