gomi no dasikata ga wakaranai toki ha, kanrinin ni kikeba ii desu.

出し方（だしかた） means the way to put something out or how to dispose of something, depending on context.

It is made from:

• 出す = to put out / take out
• the stem 出し
• 方（かた） = way of doing something

So:

• 出す → 出し方
• literally: the way of putting out

In this sentence, ごみの出し方 means how to put out the garbage or the proper way to dispose of garbage.

Here, の links two nouns.

• ごみ = garbage
• 出し方 = way of putting out

So ごみの出し方 means:

• the garbage disposal method
• more naturally, how to take out the garbage

You can think of の here as something like of or as a noun connector:

• A の B = B of A / A-related B

Examples:

• 日本語の勉強 = study of Japanese
• 車の運転 = driving a car
• ごみの出し方 = the way of putting out garbage

Because 分かる often takes が for the thing that is understood or not understood.

So:

• ごみの出し方が分からない
• literally: the way of putting out garbage is not understood
• naturally: I don’t know how to take out the garbage

This may feel unusual to English speakers, because English says I don’t know..., but Japanese often uses X が分かる / 分からない for understand / know X.

Compare:

• 意味が分かる = I understand the meaning
• 答えが分からない = I don’t know the answer

This is a very common question.

Both can relate to not knowing, but they are used differently.

• 知らない = do not know a fact / have no knowledge of it
• 分からない = do not understand / do not know how / cannot figure out

In this sentence, ごみの出し方 is about how to do something, so 分からない is more natural.

• ごみの出し方が分からない = I don’t know how to dispose of the garbage

If you said 知らない, it would sound more like:

• I have never learned that information
• not impossible, but less natural here

A useful shortcut:

• facts/names/people: often 知らない
• methods/meanings/answers: often 分からない

とき means when or at the time when.

In this sentence:

• 分からないとき = when you don’t know
• 分からないときは = as for when you don’t know / when you don’t know, ...

The は marks that whole situation as the topic.

So the sentence structure is roughly:

• [When you don’t know how to take out the garbage], as for that situation, [asking the manager is fine].

This は often gives a sense of:

• in that case
• when that happens

管理人（かんりにん） means manager, usually of a building, apartment, or property.

The particle に marks the person you ask.

With 聞く meaning to ask, the pattern is:

• person に 聞く = ask a person

So:

• 管理人に聞く = ask the manager

Examples:

• 先生に聞く = ask the teacher
• 友だちに聞く = ask a friend
• 管理人に聞く = ask the building manager

聞けばいいです means it’s fine if you ask or you should ask.

It comes from:

• 聞く = to ask / to hear
• 聞けば = if you ask
• いいです = is good

So literally:

• if you ask, it is good

Natural English:

• you should ask
• just ask
• it would be good to ask

This grammar, -ばいい, is commonly used to give advice:

• 行けばいい = you should go
• 読めばいい = you should read it
• 聞けばいい = you should ask

Yes — 聞く can mean both to hear/listen and to ask, depending on context.

In this sentence, because the object is a person marked by に, it clearly means to ask:

• 管理人に聞く = ask the manager

Compare:

• 音楽を聞く = listen to music
• 先生に聞く = ask the teacher

This is very common in Japanese, so learners need to get used to it.

They are very different.

• 聞けばいいです = you should ask / it would be good to ask
• 聞いてもいいです = it is okay to ask / may I ask? depending on context

So:

• 聞けばいいです gives advice
• 聞いてもいいです gives permission or asks permission

In this sentence, the speaker is advising what to do, so 聞けばいいです is correct.

いいです makes the sentence polite.

Compare:

• 聞けばいい。 = plain / casual
• 聞けばいいです。 = polite

So the sentence is in a polite style overall.

A very casual version would be:

• ごみの出し方が分からないときは、管理人に聞けばいい。

Yes. Japanese often leaves out subjects when they are understood from context.

So even though the sentence does not say あなたは, the meaning is naturally:

• If you don’t know how to take out the garbage, you should ask the manager.

In Japanese, leaving out obvious subjects is normal and sounds more natural.

Yes. ごみ is often written as:

• ごみ
• ゴミ
• sometimes 塵, though that is less common in everyday writing

In practical modern Japanese, ごみ and ゴミ are the most common.

So the sentence could also appear as:

• ゴミの出し方が分からないときは、管理人に聞けばいいです。

Yes, it is natural and clear.

It means something like:

• If you don’t know how to dispose of the garbage, ask the manager.

A few close alternatives are also possible, such as:

• ごみの出し方が分からないときは、管理人に聞いてください。
  = Please ask the manager.

• ごみの出し方が分からなければ、管理人に聞いてください。
  = If you don’t know how to dispose of the garbage, please ask the manager.

But the original sentence is perfectly normal, especially for giving simple advice.