What is best way to understand & Implement Rest API 'Laravel'?

Hello good people ,

am build a web application using Laravel for a group, this group also want an android application , so my andriod friend told me that he need an api so that my mobiel app can access the registration and login data base .

SO i needed to learn API , and use a laravel lib like Passport & dingo etc

i Need from some one to draw the road to me , what to learn how to use it in laravel ? best lib ?

Again am using laravel so i need some thing that i can integrated with it .

thk in advance guys .