gruppa

/ɡruppa/

Cases

SingularPluralWhen to use it
nominativegruppathe groupgruppalathe groupsthe plain dictionary form — the doer of the sentence
genitivegruppanıthe group'sgruppalanıthe groups'the owner — whose it is
accusativegruppanıthe group (as the object)gruppalanıthe groups (as the object)a specific, known object — whom or what
dativegruppağato the groupgruppalağato the groupsdirection or recipient — to where, to whom
locativegruppadaat / in the groupgruppaladaat / in the groupswhere it is; also having — mende bar, "I have it"
ablativegruppadanfrom the groupgruppaladanfrom the groupswhere 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
mygruppammy groupgruppalarımmy groups
yourgruppangyour groupgruppalarıngyour groups
his / hergruppasıhis / her groupgruppalarıhis / her groups
ourgruppabızour groupgruppalarıbızour groups
you all'sgruppağızyou all's groupgruppalarığızyou all's groups
theirgruppalarıtheir groupgruppalarıtheir groups

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