Apply means to put on a surface, like to apply makeup to your face before work. Apply also means to ask in a formal way. Long before you applied the makeup, you had to apply for the job.
You can apply the word apply to many situations, including when you make use of something — like when you apply the brakes on a car. Apply also means to really put effort into a task, like to apply yourself to learning Greek or reaching the next level on your favorite video game. But then again, maybe those examples don’t apply.