showing a php page on a WP page!

You could either use a plugin like PHP Exec, which allows you to put PHP code directly into a page, or create a custom page template, and in the template file for that page, either add your PHP code directly, or just have it include lol.php

I prefer the custom page template method myself, and it is very easy to do.

You basically just duplicate your template’s page.php file, call it something like page-lol.php, and add a header like this:

<?php
/*
Template Name: lol
*/
?>

Then when editing your page, just specify the page template to use.

More info: https://codex.www.ads-software.com/Pages#Creating_Your_Own_Page_Templates

if i want to address that lol.php on a WP page! What shall i write in the WP page after installing “PHP Exe”?

<? php …. ???

You could try something like:

<?php include "lol.php"; ?>

You may have to change that depending on where the lol.php file is stored.

if my blog is:

root/index.php
root/wp-admin

and
lol pages is on

root/lolpage/lol.php

will the code be like:
<?php include “../lolpage/lol.php”; ?>