Źrenica jest mała.

A rough guide is zhreh-NYEE-tsa yest MA-wa.

A few important details:

• ź is a soft sound, softer than the zh in measure
• ni in źrenica sounds a bit like nyi
• jest sounds like yest
• ł in mała sounds like English w

Stress usually falls on the second-to-last syllable:

• źre-NI-ca
• MA-ła

Because in Polish, most nouns ending in -a are grammatically feminine. Źrenica is one of them.

This is grammatical gender, not biological sex. Since źrenica is feminine, other words connected to it must match that gender:

• ta źrenica
• mała źrenica
• źrenica jest mała

Polish adjectives must agree with the noun in gender, number, and case.

Since źrenica is:

• feminine
• singular
• nominative

the adjective must also be feminine singular nominative:

• mała

Compare:

• mały — masculine
• mała — feminine
• małe — neuter

It is nominative singular, because it is the subject of the sentence.

The adjective mała is also nominative singular feminine, because it describes the subject after jest.

Jest means is. It is the 3rd person singular form of być (to be).

In a normal standard sentence like this, you use it:

• Źrenica jest mała.

Leaving it out would sound non-standard, very elliptical, or poetic rather than normal everyday Polish.

Polish does not use articles like English the and a/an.

So źrenica can mean:

• the pupil
• a pupil

The exact meaning depends on context, not on a separate article.

Because here mała is part of the predicate with jest, not just an adjective inside a noun phrase.

Compare:

• mała źrenica = a small pupil / the small pupil
• Źrenica jest mała = The pupil is small

So in your sentence, mała comes after jest because it is saying something about the subject.

Yes, Polish word order is flexible, but Źrenica jest mała is the most neutral and natural version.

For example:

• Mała jest źrenica puts extra emphasis on mała

As a learner, the safest version is:

• Źrenica jest mała

Not here.

Use jest when describing something with an adjective:

• Źrenica jest mała. = The pupil is small.

Use to mainly when identifying or defining something with a noun:

• To jest źrenica. = This is a pupil.
• Źrenica to część oka. = The pupil is a part of the eye.

So with mała, you need jest, not to.

The plural sentence is:

• Źrenice są małe. = The pupils are small.

Changes:

• źrenica → źrenice
• jest → są
• mała → małe

They are both important Polish letters with their own pronunciation:

• ź is a soft consonant, different from ż or rz
• ł is pronounced like English w

So:

• źrenica must be spelled with ź, not ż
• mała does not have an English-style l sound in it