Ta uczennica czyta po polsku coraz lepiej, chociaż nadal boi się mówić przed innymi.

Because uczennica is a feminine noun, and the demonstrative ta must agree with it in gender.

• ten = this (masculine)
• ta = this (feminine)
• to = this (neuter)

So:

• ta uczennica = this female pupil/student

Uczennica means a female pupil or female school student.

It is the feminine form of uczeń.

For an English speaker, it helps to know that Polish often distinguishes male and female forms more clearly than English:

• uczeń = male pupil/student
• uczennica = female pupil/student

In many contexts, studentka would usually mean a female university student, while uczennica normally refers to someone at school.

Po polsku is the standard Polish expression meaning in Polish.

This pattern is very common with languages:

• po polsku = in Polish
• po angielsku = in English
• po niemiecku = in German

So czyta po polsku means she reads in Polish.

Even though English uses in, Polish uses po + adjective form here.

More naturally, it means she reads in Polish.

That is, the language of the text or the language she is using is Polish.

If you wanted to say she reads Polish in the sense of she studies the Polish language, that would usually need a different wording depending on the context.

So here, think of po polsku as describing how / in what language she reads.

Coraz lepiej means better and better or increasingly well.

It is a very common Polish pattern:

• coraz = increasingly / more and more
• lepiej = better / more well

Together:

• coraz lepiej = better and better

Other examples:

• coraz szybciej = faster and faster
• coraz trudniej = more and more difficultly / harder and harder
• coraz więcej = more and more

Because lepiej is an adverb, and it describes the verb czyta (reads).

You need an adverb when you describe how someone does something:

• czyta dobrze = she reads well
• czyta lepiej = she reads better

By contrast, lepszy / lepsza / lepsze are adjectives, used to describe nouns:

• lepsza książka = a better book
• lepszy uczeń = a better student

So:

• She reads better → czyta lepiej
• She is a better student → jest lepszą uczennicą / to lepsza uczennica

Bać się is simply the normal Polish verb meaning to be afraid or to fear.

So the full dictionary form is:

• bać się = to be afraid

In the sentence:

• boi się = she is afraid

Many Polish verbs use się, and it does not always translate directly into English as herself or oneself. In this case, you should learn bać się as one whole verb.

Because after bać się, Polish can use an infinitive to say to be afraid to do something.

So:

• boi się mówić = she is afraid to speak

This is very similar to English:

• She is afraid to speak

Other examples:

• boję się zapytać = I’m afraid to ask
• boją się wejść = they are afraid to go in

Chociaż means although, though, or even though.

It introduces a clause that contrasts with the first part of the sentence:

• Ta uczennica czyta po polsku coraz lepiej
  chociaż nadal boi się mówić przed innymi.

So the idea is:

• she is improving in one area,
• although she still has difficulty or fear in another area.

It is a conjunction introducing a subordinate clause.

Because in Polish, a subordinate clause introduced by words like chociaż, że, bo, kiedy, jeśli, etc. is normally separated by a comma.

So:

• ..., chociaż nadal boi się mówić...

This is standard Polish punctuation.

Nadal means still.

So:

• nadal boi się = she is still afraid

Its position is natural because it modifies the whole idea that she continues to be afraid.

Polish word order is somewhat flexible, but nadal often appears before the verb phrase it modifies.

Innymi is in the instrumental case because of the preposition przed.

Here, przed innymi means:

• in front of others
• before others
• with other people present

After przed, Polish often uses the instrumental case when it means in front of or in the presence of:

• przed nauczycielem
• przed klasą
• przed innymi

The base form is inni = others, and the instrumental plural is innymi.

Polish can use inni and its case forms by themselves to mean other people or others, just like English can say others without a noun.

So przed innymi naturally means:

• in front of others
• in front of other people

The noun ludźmi is not necessary, although in some contexts Polish could say przed innymi ludźmi for extra clarity or emphasis.

Yes, Polish word order is more flexible than English, though not completely free.

The given sentence is neutral and natural:

• Ta uczennica czyta po polsku coraz lepiej, chociaż nadal boi się mówić przed innymi.

You could change the order a little for emphasis, for example:

• Ta uczennica coraz lepiej czyta po polsku, chociaż nadal boi się mówić przed innymi.

This still sounds natural.

But not every rearrangement sounds equally good, and the original version is a very standard one.

Yes, very often. It is the normal way to say that something happens in a language.

For example:

• mówi po polsku = she speaks Polish / she speaks in Polish
• czyta po polsku = she reads in Polish
• pisze po polsku = she writes in Polish

So this pattern is extremely useful and worth memorizing.