Satisfacer vs. cumplir
In the Spanish language, 'satisfacer' and 'cumplir' are both verbs that translate to 'to satisfy' and 'to fulfill' respectively in English. Even though they may seem similar at first glance, they are used in different contexts and do not mean exactly the same thing.
Satisfacer
The word 'satisfacer' in Spanish is used when referring to meeting or fulfilling a need, requirement, or desire.
Esta comida debería satisfacer tu hambre.
(This food should satisfy your hunger.)
El objetivo de nuestro negocio es satisfacer las necesidades de nuestros clientes.
(The aim of our business is to satisfy the needs of our customers.)
Es un artista que siempre busca satisfacer su deseo de ser creativo.
(He is an artist who always seeks to satisfy his desire to be creative.)
Cumplir
'Cumplir' is generally used when referring to achieving something that was promised, expected or required. It also means carrying out an action or executing a duty.
Es importante cumplir con nuestras promesas.
(It's important to keep our promises.)
Ella siempre cumple sus responsabilidades en el trabajo.
(She always fulfills her responsibilities at work.)
Es mi obligación como ciudadano cumplir con la ley.
(It's my duty as a citizen to obey the law.)
Summary
'Satisfacer' and 'cumplir', although related, are used differently in Spanish. While 'satisfacer' refers to satisfying desires or needs, 'cumplir' has a more broad usage and usually involves fulfilling a promise, expectation, obligation or duty.