insatu ga owattara, siryou wo hottikisu de matomemasu.

Because 印刷が終わる is the pattern here.

In this sentence, 終わる is an intransitive verb, meaning something finishes / ends on its own:

• 印刷が終わる = the printing finishes
• 会議が終わる = the meeting ends

With intransitive verbs, the thing that undergoes the change is often marked by が.

If you used を, you would usually need a transitive verb such as 終える:

• 印刷を終えたら = when (someone) finishes the printing

So:

• 印刷が終わったら focuses on the printing being finished
• 印刷を終えたら focuses more on someone finishing the printing

Both can work, but this sentence uses the more natural event-based phrasing.

終わったら means when it finishes or after it has finished.

It is made from:

• 終わる = to finish, to end
• 終わった = finished / ended
• 終わったら = if/when it finishes; after it finishes

The 〜たら form often means:

• when
• after
• sometimes if

In this sentence, the natural meaning is:

• When the printing is finished, ...
• After the printing is finished, ...

So 印刷が終わったら、... sets up the condition or timing for the next action.

Here it most naturally means when / after.

That is because the sentence describes a normal sequence of events:

1. the printing finishes
2. then the documents are stapled together

So although 〜たら can mean if, this sentence is not really expressing uncertainty in the English sense. It is more like:

• When the printing is done, I’ll staple the documents together.

A good way to think about it here is:

• once X happens, Y happens

Because 資料 is the direct object of まとめます.

• 資料 = documents / materials
• 資料をまとめます = put the documents together / compile the documents

So を marks the thing being acted on.

The structure is:

• 印刷が終わったら = when the printing is finished
• 資料を = the documents
• ホッチキスで = with a stapler
• まとめます = put together / organize / compile

Good question. まとめる has several related meanings, and one of them is indeed to summarize. But its core idea is to gather things together into one organized whole.

Common meanings include:

• to put together
• to gather
• to organize
• to compile
• to summarize

In this sentence, because of ホッチキスで, it clearly means something like:

• to put the documents together
• to staple the documents together into one set

So it is not summarize here. The stapler tells you the meaning is physical, not abstract.

In Japanese, ホッチキス usually means a stapler.

So:

• ホッチキスで = with a stapler

It does not usually mean the staple itself.

A useful note: ホッチキス is a common Japanese word, but it comes from a brand name historically. In everyday Japanese, though, people widely use it to mean stapler.

Here, で marks the tool or means used to do the action.

So:

• ホッチキスでまとめます = put them together with a stapler

This is the same で used in sentences like:

• ペンで書きます = write with a pen
• はさみで切ります = cut with scissors
• バスで行きます = go by bus

So で often tells you by means of / using.

Yes, most likely.

Japanese often leaves out the subject when it is obvious from context. This sentence does not explicitly say who will do the stapling.

Depending on context, it could mean:

• I’ll staple the documents together when the printing is finished.
• We’ll staple the documents together when the printing is finished.
• Please staple the documents together when the printing is finished.
  
  • though that would more naturally be phrased differently if it were a direct instruction

Because the verb is まとめます, which is polite non-past, the sentence could be a neutral statement about what the speaker will do, or part of procedural language.

Yes. まとめます is the polite ます-form of まとめる.

So the sentence is in polite style. This is common in:

• workplace instructions
• manuals
• formal conversation
• speaking politely to someone

Notice that the earlier part, 終わったら, is not in ます-form. That is normal. In Japanese, subordinate clauses often use plain forms even in polite sentences.

So this combination is perfectly natural:

• 印刷が終わったら、資料をホッチキスでまとめます。

The comma helps separate the when/after clause from the main action.

• 印刷が終わったら、 = when the printing is finished,
• 資料をホッチキスでまとめます。 = I put the documents together with a stapler.

Japanese commas are often used more flexibly than English commas, but here it makes the sentence easier to read by clearly marking the transition from the condition/time clause to the main clause.

It is very natural to include the comma here.

Not exactly. That English version can sound like after I do the act of printing. The Japanese is slightly different.

印刷が終わったら literally means:

• when the printing has finished
• after the printing is done

That focuses on the completion of the printing process, not necessarily on who performed it.

So better translations would be:

• When the printing is finished, I staple the documents together.
• After the printing is done, I staple the documents together.

No, that is not correct.

You should say either:

• 印刷が終わったら
  = when the printing is finished

or

• 印刷を終えたら
  = when I/you/someone finish(es) the printing

The reason is that:

• 終わる is intransitive, so it goes with が
• 終える is transitive, so it goes with を

So 印刷を終わったら incorrectly mixes を with 終わる.

It can be either, depending on context.

Japanese nouns usually do not mark singular/plural the way English does. So 資料 could mean:

• a document
• documents
• materials

In this sentence, because of the action ホッチキスでまとめます, it most naturally means documents or a set of papers/materials.

So English often translates it as plural, even though Japanese does not explicitly mark that.