In English we tack 's onto the end of a name or a noun to say that something belongs to that person or object.
The equivalent in French is the little word de (of). For example:
Play audio La jupe de Catherine = Catherine's skirt
Note that this literally translates to "The skirt of Catherine."
As you'd probably expect, when you put de in front of a vowel, it contracts into d':
Play audio La chemise d'Antoine = Antoine's shirt
When the object belongs to a group of people, the de turns into a des. Notice that the s sound in des is silent:
Play audio La chambre des parents = The parents' bedroom
But it's not so silent when you put the des in front of a vowel. Here it turns into something like a Z sound to make pronunciation less awkward:
Play audio La chambre des enfants = The children's bedroom