pain – el dolor
(Pronounced doh-lor)
To remember that pain is pronounced doh-lor (dolor) in Spanish, use the following mnemonic:
He said he could relieve her pain but it would cost her a dollar (dolor).

Pain is masculine so it' el dolor, imagine an elephant inflicting pain:

Examples of dolor (pain) in a sentence
Tengo dolor de espalda.
(I have back pain.)
Siento un dolor agudo aquí.
(I feel a sharp pain here.)
¿Tiene dolor en el pecho?
(Do you have chest pain?)