Numer karty bibliotecznej widzę na koncie czytelnika w czytelni.

Polish word order is much freer than English word order because the case endings show what each noun is doing.

Starting with Numer karty bibliotecznej puts extra focus on that item. It is a bit like saying:

As for the library card number, I can see it on the reader’s account in the reading room.

A more neutral order would be:

Widzę numer karty bibliotecznej na koncie czytelnika w czytelni.

So the original word order is not wrong; it is just more marked and more focused.

Because numer is a masculine inanimate noun, and in Polish the singular accusative of masculine inanimate nouns is the same as the nominative.

So:

• nominative: numer
• accusative: numer

Even though the form looks the same, its function here is accusative, because it is the thing being seen.

You can compare that with a masculine animate noun:

• nominative: czytelnik
• accusative: czytelnika

That is why numer stays numer, but czytelnik changes to czytelnika in other contexts.

Because Polish uses the genitive after numer.

The pattern is:

numer czego? = the number of what?

So:

• numer karty = card number / number of the card

Since karta is feminine singular, its genitive form is karty.
The adjective must match it, so:

• karta biblioteczna becomes
• karty bibliotecznej

So the whole phrase means literally:

number of the library card

Because in Polish, with accounts, profiles, pages, and similar places where information appears, na is often the normal idiomatic preposition.

So Polish says:

• na koncie = on the account
• na profilu = on the profile
• na stronie = on the page

It does not mean something is physically lying on top of the account. It is just the natural Polish way to express where the information appears.

So w koncie would sound wrong here.

Because after na in the meaning of location, Polish uses the locative case.

Here na koncie means on the account as a place where something is located.

The noun changes like this:

• basic form: konto
• locative singular: koncie

So:

• na koncie = on the account

Here czytelnika depends on koncie:

konto czytelnika = the reader’s account / the patron’s account

Polish often uses the genitive to show this kind of possession or relationship.

The pattern is:

konto kogo? = whose account?

Answer:

czytelnika

So czytelnika is genitive singular here.

Literally, czytelnik means reader. But in a library context it often means:

• library user
• library patron
• registered reader

So in this sentence, it does not necessarily mean someone who is actively reading at that moment. It can simply mean a person who has a library account or library card.

Because w with the meaning of location takes the locative case.

The basic form is:

• czytelnia = reading room

After w, it becomes:

• w czytelni = in the reading room

So this is the same kind of change as:

• biblioteka → w bibliotece
• szkoła → w szkole

Not exactly. Czytelnia usually means reading room, a specific room or area for reading or consulting materials.

So:

• biblioteka = library
• czytelnia = reading room

That is an important distinction. If the English meaning shown to the learner says library, you should know that the Polish word here is more specific.

Widzę is the 1st person singular present tense of widzieć, which means to see.

It is the normal choice when you mean that you can currently see something.

So:

• widzę = I see / I can see

This is an imperfective verb, and that is natural here, because the sentence describes an ongoing perception, not a single completed moment of noticing.

A perfective verb such as zobaczyć would give a different meaning, more like I will see or I catch sight of.

It is understandable, but the final phrase w czytelni can attach a little loosely.

The most natural reading is probably:

In the reading room, I see the library card number on the reader’s account.

But because Polish allows flexible word order, a learner may wonder exactly what w czytelni modifies.

If you want to make it clearer, you can move it:

• W czytelni widzę numer karty bibliotecznej na koncie czytelnika.

That makes the location of the whole action clearer.

So the original sentence is grammatical, but the placement of w czytelni is something a learner might notice as slightly open to interpretation.