Is it possible to insert text into an html tag using functions.php?

Here’s what I mean:

I am using a plugin called ‘pods’ which allows for the creation of Custom (CPT) and for relationships to be formed between those CPT’s.

However – there’s a little flaw that I can see in that I have created a CPT for US States, so each CPT is one individual state which means that each post that is created within this CPT just has the title of the state.

Here’s the HTML and associated CSS

<header class="entry-header clr">
    <h2 class="single-post-title entry-title" >123 Florida</h2><!-- .single-post-title -->
</header><!-- .entry-header -->

I would like to be able to add some text where it says ‘123’.

I am thinking that I can re-use a functions snippet I came across which replaces some CSS (in this instance it hides the ‘remember me’ check box at the login).

function do_not_remember_me()
{
echo '<style type="text/css">.forgetmenot { display:none; }</style>';
}
add_action('login_head', 'do_not_remember_me');

The fact that I know the CSS classes ‘ought’ to be enough right?

Thanks for all help/ direction