So to help remedy the steep climb that is required in learning how to use Laravel, here are some PHP concepts that Laravel uses heavily that I recommend reading up on before you dive in:
Inheritance — Basics but you need to start somewhere. http://php.net/manual/en/language.oop5.inheritance.php
Autoloading/PSR-4 — Not required but good to know http://www.php-fig.org/psr/psr-4
Traits — Already used in Laravel 4 but good to know http://www.sitepoint.com/using-traits-in-php-5-4
Dependency Injection — Used a lot in Laravel 5 http://code.tutsplus.com/tutorials/dependency-injection-in-php--net-28146
Hopefully some of that info will help you on your way. If you want to dive a bit deeper into Laravel 5 I can recommend the Laracasts — What’s New in Laravel 5.0 series, full of helpful info and tips.