In Spanish, the letter c when accompanied by the vowels "a, o, u" is pronounced as "k". When it is accompanied by the vowels "e, i" it is pronounced in two different forms: In Latin America it is pronounced as an "s", in Spain it is pronounced as "th" as in the word "thief. The letter z is pronounced the same with all vowels: In Latin America as an "s" and in Spain as a "th" also.

Note: The examples below are pronounced in the Latin American accent.
c
Caballo café.
     Brown horse.
Ese cepillo es nuevo.
     That brush is new.
Estoy de vacaciones.
     I'm on vacation.
Cocina la cena.
     Cook dinner.
¿Cuánto cuesta?
     How much is it?
z
Mis zapatos son cafés.
     My shoes are brown.
Yo veo cinco zebras.
     I see five zebras.
El zíper es azul.
     The zipper is blue.
La zorra está en el zoológico.
     The female fox is in the zoo.
Ella tiene una manzana.
     She has an apple.