Gracias usually means "thank you" o "thanks". "Thank you very much" in Spanish is Muchas gracias.
However the expression Por favor can have several meanings.
In general, it means "please" and is used to ask for something:
Una cerveza, por favor – A beer, please
The Spanish use it a lot. Even if you just point to something in order to ask it, make sure to add
Esto, por favor – This one, please
The long phrase "Could you tell me the way to" can also be expressed in two words, por favor!
¿El Prado, por favor? – Could you tell me the way to El Prado, please?
Finally, to express your outrage softly, you should say por favor stressing both words:
¡Por favor! – What is all this mess?
When we accept something, we usually say Sí, por favor. However we say No, gracias when we reject it, compare:
– ¿Quieres un café? – Want a coffee?
– Sí, por favor
– ¿Quieres un café?
– No, gracias