Arahat/Arahant : Buddhist spiritual practitioner who has realized last stage of attainment.
(Buddha) Dhamma: Teachings of his holiness Buddha.
Parinirvana: Those who have achieved enlightenment to the last stage ( are called arahats ) are not born again or do exist after death. in any other form. it is their last life and they vanish after death like a candle completely burned ending the sufferings of existence.
Sangha/ Bhikku/ Monk : Followers of lord Buddha committed to spiritual life.
Tripitaka: collectively 3 sections of Dhamma ( teaching of Buddha ).