The /s/ and /z/ sounds are both producing in the same way differing only in voicing (vibration of the vocal folds) with the /s/ being unvoiced (with your voice turned off) and the /z/ being voiced (with your voice turned on).
The /z/ sound can be written several different ways. For example:
/s/ toys, please
/z/ squeeze, zebra
/x/ xylophone, xenon
Additionally, the /s/ and /z/ sounds are also grammatical markers. Plurals, possessives and noun-verb agreement all require the use of the /s/ and /z/ sound. For example:
She plays (noun-verb agreement)
Two cats and two dogs (plurals)
Mom’s car (possessives)
The /z/ sound can be written several different ways. For example:
/s/ toys, please
/z/ squeeze, zebra
/x/ xylophone, xenon
Additionally, the /s/ and /z/ sounds are also grammatical markers. Plurals, possessives and noun-verb agreement all require the use of the /s/ and /z/ sound. For example:
She plays (noun-verb agreement)
Two cats and two dogs (plurals)
Mom’s car (possessives)