The letter K is a letter of relatively little use in syllables of the Spanish Native Language. Their sound is the same regardless of the vowel accompanying:
In Spanish, the letter C is one of the few that changes its sound depending on the vowel that accompanies. When accompanied with the vowels “a”, “o” and “u” sounds identical to the K, i.e.:
When it is accompanied by the vowels “i” and “e”, its sound is identical to that of the syllables formed with the letter S:
Moreover, the sound of the vowels with the letter Z happens something similar to what we saw with B and V. In everyday speech of Hispanic Countries, the sounds of the syllables with Z and S is practically the same. The exception (and only really correct) is Spain, where the correct sound of the syllables formed by Z and any vowel with the right “hiss” is used.