pes

/pes/

Cases

SingularPluralWhen to use it
nominativepesthe fezpeslethe fezesthe plain dictionary form — the doer of the sentence
genitivepesnithe fez'speslenithe fezes'the owner — whose it is
accusativepesnithe fez (as the object)peslenithe fezes (as the object)a specific, known object — whom or what
dativepesgeto the fezpeslegeto the fezesdirection or recipient — to where, to whom
locativepesdeat / in the fezpesledeat / in the fezeswhere it is; also having — mende bar, "I have it"
ablativepesdenfrom the fezpesledenfrom the fezeswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
mypesimmy fezpeslerimmy fezes
yourpesingyour fezpesleringyour fezes
his / herpesihis / her fezpeslerihis / her fezes
ourpesibizour fezpesleribizour fezes
you all'spesigizyou all's fezpeslerigizyou all's fezes
theirpesleritheir fezpesleritheir fezes

The overlap in the last rows is real, not a mistake: pesleri can mean "his / her fezes", "their fez", or "their fezes" — context decides.