Članska karta je u ormariću u svlačionici.

• članska = membership / member’s
• karta = card
• je = is
• u = in
• ormariću = locker / small cabinet
• u svlačionici = in the changing room / locker room

So the structure is literally:

membership card is in locker in changing room

Natural English: The membership card is in the locker in the changing room.

Because karta is a feminine noun, and the adjective has to agree with it in gender, number, and case.

• masculine: članski
• feminine: članska
• neuter: člansko

Since karta is feminine singular, the correct form is članska.

Both are in the locative singular.

That is because they follow u in the meaning of in / inside, which expresses location, not motion.

• u ormariću = in the locker
• u svlačionici = in the changing room

A very useful rule:

• u + locative = in/at somewhere
• u + accusative = into somewhere

Compare:

• Karta je u ormariću. = The card is in the locker.
• Stavljam kartu u ormarić. = I am putting the card into the locker.

Because there are two nested locations:

• u ormariću = in the locker
• u svlačionici = in the changing room

So the sentence means the card is in one place, and that place is itself inside another place.

English does the same: in the locker in the changing room

Their dictionary forms are:

• ormarić = locker, small cabinet
• svlačionica = changing room, locker room

The forms in the sentence are locative singular:

• ormarić → u ormariću
• svlačionica → u svlačionici

Yes. Ormarić comes from orman/ormar-type vocabulary meaning a cabinet or wardrobe, and -ić often gives a smaller or more specific sense.

So ormarić often means:

• a small cabinet
• a locker

In everyday usage, u ormariću is a very natural way to say in the locker.

Normally, no. In a full neutral sentence like this, je is needed because it is the 3rd person singular of biti (to be):

• Članska karta je u ormariću. = The membership card is in the locker.

In some very informal notes, headlines, or elliptical speech, people may drop forms of to be, but for standard learning purposes you should keep je.

The given order is the most neutral and natural:

Članska karta je u ormariću u svlačionici.

Serbian word order is fairly flexible, but changing it usually changes emphasis, not basic meaning.

For example:

• U ormariću u svlačionici je članska karta.
  = The membership card is in the locker in the changing room.
  This puts more focus on the location.

• U svlačionici je članska karta u ormariću.
  Still understandable, but less neutral.

As a learner, the original order is the safest choice.

A rough guide:

• č = like ch in chocolate, but usually a bit harder
• ć = a softer sound, somewhat like a very soft ty/ch sound
• čl at the start of članska can feel awkward for English speakers; try saying it slowly: ch-lan-ska

Approximate pronunciation of the whole sentence:

CHLAN-ska KAR-ta ye oo or-MA-ri-chyoo oo svla-cho-NI-tsi

A few notes:

• je is pronounced roughly ye
• c in svlačionici is pronounced ts
• stress is not usually marked in normal writing

Yes. Karta is a broad word and can mean different things depending on context, including:

• card
• ticket
• map

So članska karta specifically means membership card.

Other examples:

• autobuska karta = bus ticket
• geografska karta = map
• lična karta = ID card

Context tells you which meaning is intended.

Yes, svlačionica is a correct and common word for changing room / locker room.

Depending on region and situation, you may also hear words like:

• garderoba in some contexts
• other local preferences in Bosnian/Croatian/Serbian usage

But svlačionica is perfectly clear and standard.

In Serbian Cyrillic, it is:

Чланска карта је у ормарићу у свлачионици.

Letter by letter:

• Č → Ч
• ć → ћ
• š → ш
• c → ц

Serbian is normally written in both Latin and Cyrillic, and the meaning is exactly the same.

Serbian has no articles like a/an/the.

So:

• Članska karta can mean a membership card or the membership card
• u ormariću can mean in a locker or in the locker

The exact meaning comes from context. In this sentence, English naturally uses the: The membership card is in the locker in the changing room.

But Serbian does not need a separate word for that.