Learn Hardcore Japanese: kyousitu no kabe ni ha, hatuon no pointo ga kaite aru posutaa ga hatte arimasu. - On the classroom wall, there are posters stuck up with pronunciation tips written on them.

That’s still correct, just a bit more neutral and less “topic-y”. The version with には sounds more like you’re describing the room, or contrasting that wall with somewhere else (e.g., the door, the ceiling, etc.).

What exactly does 貼ってあります mean? How is it different from just あります or 貼っています?

貼ってあります is 貼る (to stick/paste/put up) in the pattern ～てある, which expresses:

a resulting state caused by someone’s intentional action.

So:

ポスターが貼ってあります。
= Posters have been put up (and are there now).
(Someone stuck them there on purpose, and they are still up.)

Compare:

ポスターがあります。
= There are posters.
Only states existence. No information about how they are placed.
ポスターが貼っています。
Grammatically possible, but:
- Often suggests an ongoing action (someone is currently sticking them up), or
- Sounds less natural than 貼ってある when describing something that was put up beforehand and is now there as a result.

For posters on a wall (already prepared and left there), 貼ってあります is the most natural: it highlights that they have been put up for a reason (for study, decoration, etc.) and are currently in that state.

What does the pattern ～てある (as in 書いてある, 貼ってある) mean?

～てある = te-form of a transitive verb + ある, and it expresses:

A current state that is the result of someone’s deliberate action.

In this sentence:

書いてある (from 書く, “to write”)
= are written (and are there now as a result of somebody writing them).
貼ってある (from 貼る, “to stick/put up”)
= have been put up and remain in that state.

Key points:

It is not the same as a simple past tense like 書いた or 貼った.
It focuses on the present result, not on when the action happened.
English often translates it as a passive:
発音のポイントが書いてある → the pronunciation points are written
but grammatically in Japanese it’s a resultative form, not a passive.

How does 発音のポイントが書いてあるポスター work grammatically? Why is the verb before ポスター?

This is a relative clause, which in Japanese always comes before the noun it modifies.

発音のポイントが書いてある modifies ポスター.

So:

発音のポイントが書いてあるポスター
= [発音のポイントが書いてある]ポスター
= posters on which pronunciation points are written
= posters that have pronunciation tips written (on them).

Inside this mini-sentence:

発音のポイント = pronunciation points / tips
が = subject marker
書いてある = are written (result of someone writing them)

The subject who wrote them (e.g. the teacher) is omitted because it’s obvious from context.

So the big structure is:

教室の壁には、[発音のポイントが書いてあるポスター]が貼ってあります。
On the classroom wall, [posters that have pronunciation tips written on them] have been put up.

Why are there two が in the same sentence: 発音のポイントが書いてあるポスターが貼ってあります? Isn’t that wrong?

It’s fine because the two が belong to different clauses.

Break it down:

発音のポイントが書いてある
- A relative clause modifying ポスター
- Here, 発音のポイント is the subject, marked by が.
ポスターが貼ってあります
- The main clause
- Here, ポスター is the subject, marked by が.

So the structure is:

[発音のポイントが書いてある]ポスターが貼ってあります。

Having multiple が is only a problem when you try to have more than one subject in the same simple clause. With nested clauses (like relative clauses), multiple が is completely normal.

What does 発音のポイント mean? Does ポイント here mean “dot/point” like in math?

In this context, ポイント is a loanword from English “point” meaning:

key point / tip / important aspect

So:

発音のポイント
= key points of pronunciation
= pronunciation tips / pronunciation highlights

It does not mean physical dots or points on a line. It means points in the sense of:

“The important points about pronunciation are written here.”

A very similar idea in more native-looking Japanese would be:

発音のコツ (tips for pronunciation)
発音の大事な点 (important points of pronunciation)

Why 教室の壁 and not just 教室に? Would 教室にポスターが貼ってあります work?

教室にポスターが貼ってあります is grammatically fine and means:

There are posters put up in the classroom.

However, 教室の壁には adds a more specific location:

教室に = in the classroom (somewhere inside)
教室の壁に = on the classroom wall

Since posters are typically stuck to walls, mentioning 壁 (wall) gives a clear picture and can contrast that location with other possible places (on the door, on the board, hanging from the ceiling, etc.).

So:

教室には、発音のポイントが書いてあるポスターが貼ってあります。
= In the classroom, such posters have been put up.
教室の壁には、発音のポイントが書いてあるポスターが貼ってあります。
= On the classroom wall, such posters have been put up. (More specific.)

Can I change the word order, like 発音のポイントのポスターが壁に貼ってあります? Is that the same?

発音のポイントのポスター is not wrong, but it means something slightly different, and it loses some nuance.

発音のポイントが書いてあるポスター
= posters on which pronunciation tips are written
(Focus: the content is literally written on the poster.)
発音のポイントのポスター
= posters of pronunciation points / posters about pronunciation points
(More like “posters about the topic of pronunciation points”, without saying that the points are written on them.)

Also, relative clauses in Japanese must come immediately before the noun they modify. So structures like:

✗ 発音のポイントのポスターが書いてある (sounds like “the posters of pronunciation points are written” – odd)
✗ ポスターが発音のポイントが書いてある (two が in the same simple clause; ungrammatical)

are not correct in the intended meaning.

The original order:

[発音のポイントが書いてある]ポスターが[壁に]貼ってあります。

is the natural and precise way to say “posters with pronunciation tips written on them are stuck on the wall.”

Why is it あります and not います or です at the end?

Because we’re talking about inanimate objects (posters), and we’re expressing existence/state, not equating A = B.

あります is used for inanimate things:
- 本があります。 = There is a book.
- ポスターが貼ってあります。 = Posters have been put up (exist in that state).
います is used for animate beings (people, animals):
- 学生がいます。 = There is a student.
- 先生が教室にいます。 = The teacher is in the classroom.
です links a subject and a complement:
- これはポスターです。 = This is a poster.
- 教室はきれいです。 = The classroom is clean.

In 貼ってあります, ある is functioning in the ～てある pattern, showing that the posters exist in the state of having been put up.

What is the role of the comma after には (教室の壁には、)? Does it change the meaning?

The comma is just a pause marker; it does not change grammar or core meaning.

教室の壁には、発音のポイントが書いてあるポスターが貼ってあります。
教室の壁には発音のポイントが書いてあるポスターが貼ってあります。

Both are correct.

The comma:

makes it easier to read by visually separating the topic (教室の壁には) from the rest of the sentence,
corresponds to a natural pause when speaking.

Japanese commas are often used after longer topic phrases (Xは、...), but are generally optional.

Is 書いてある present tense or past tense? How should I feel the time aspect?

書いてある focuses on the current state resulting from a past action.

Somebody wrote the pronunciation points at some earlier time.
As a result, now they are written there.

So it has:

Past action in the background (someone wrote them), and
Present relevance / state in the foreground (they are now written).

English often translates this as a passive present:

発音のポイントが書いてある → The pronunciation points are written (on it).

But in terms of Japanese grammar, it’s not “present tense of 書く”; it’s 書く → 書いて + ある, a resultative pattern that describes the current situation.