kiiboodo no ue ni kami wo oite ha ikemasen.

It is the te-form + はいけません pattern, which expresses prohibition.

• 置く = to put / place
• 置いて = te-form of 置く
• 〜てはいけません = must not do ~ / it is not allowed to do ~

So:

• 置いてはいけません = You must not place it / Do not put it

This is a common grammar pattern:

• ここで食べてはいけません。 = You must not eat here.
• 入ってはいけません。 = You must not enter.

It is fairly standard and formal/polite. In casual speech, people may say 置いちゃだめ or 置いてはだめ.

Great question. In 〜てはいけません, the は is part of a set grammar pattern, not the normal topic marker in the usual sense.

Historically and grammatically, this comes from:

• 置いては
  • いけません

Here, ては often carries the sense of if one does ~ or as for doing ~, and when combined with いけません, it means something like:

• If you put it, that won’t do
• more naturally: You must not put it

So in this sentence, you should learn てはいけません as one chunk.

A related spoken contraction is:

• 〜ちゃいけません from 〜てはいけません
• example: 置いちゃいけません

Because 上 is a noun meaning top / upper part / above, and nouns are connected with の.

So:

• キーボード = keyboard
• の = linking particle, like of
• 上 = top / on top

Together:

• キーボードの上 = the top of the keyboard / on the keyboard

This is a very common pattern:

• 机の上 = on the desk
• 箱の中 = in the box
• ドアの前 = in front of the door

Many location words in Japanese act like nouns, so they often need の before them.

Because 置く is a verb of placement, and に marks the destination/location where something is placed.

• 紙をキーボードの上に置く = put paper on the keyboard

With verbs like 置く, 入れる, 座る, 乗る, Japanese often uses に to show the place something ends up.

By contrast, で usually marks the place where an action happens:

• 机の上で書く = write on the desk
• 部屋で食べる = eat in the room

So:

• に = where something is placed / exists / goes
• で = where an action takes place

Because 紙 is the direct object of 置く.

• 紙 = paper
• を = marks the thing being acted on
• 置く = to put

So 紙を置く means to put the paper.

In other words, the paper is the thing being placed.

Compare:

• 本を置く = put a book
• かばんを置く = put down a bag

Japanese nouns usually do not show singular vs. plural the way English does.

So 紙 could mean:

• paper
• a sheet of paper
• papers

The exact meaning depends on context.

In this sentence, English might naturally translate it as:

• Do not place paper on the keyboard.
• Do not put a sheet of paper on the keyboard.
• Do not put papers on the keyboard.

All of these could fit depending on the situation.

Yes. In this sentence, 上 is read うえ.

So the sentence is read:

キーボード の うえ に かみ を おいて は いけません。

Useful readings here:

• 上（うえ） = above / on top
• 紙（かみ） = paper
• 置いて（おいて） from 置く（おく）

Be careful not to confuse:

• 置く（おく） = to place
• おく as an auxiliary in other contexts, as in 〜ておく

Here it is just the regular verb 置く.

It usually means must not or do not, so it is a fairly strong prohibition.

Depending on context, it can sound like:

• a rule
• an instruction
• a warning
• something not allowed

So this sentence sounds like:

• Do not put paper on the keyboard.
• You must not place paper on the keyboard.

It is stronger than a mild suggestion like You shouldn’t.

Some related expressions:

• 〜ないでください = please don’t do ~
  Slightly softer in many contexts.
• 〜てはだめです = you must not / it’s no good to ~
  Similar meaning, often a bit more conversational.
• 〜ちゃだめ = don’t ~
  Casual.

Yes. Natural Japanese is normally written without spaces:

キーボードの上に紙を置いてはいけません。

The spaced version is usually only for learners, textbooks, or very early reading practice.

So both are the same sentence, but the version without spaces is what you would normally see.

Yes. In speech, ては is often contracted to ちゃ.

So:

• 置いてはいけません → 置いちゃいけません

And in more casual speech:

• 置いちゃだめ
• 置かないでください if you want a softer request

These are different in tone:

• 置いてはいけません。 = formal/polite rule-like statement
• 置いちゃいけません。 = spoken, still fairly strong
• 置いちゃだめ。 = casual
• 置かないでください。 = polite request, often softer

Because キーボード is a loanword from English keyboard, and loanwords are usually written in katakana.

This is very common in Japanese:

• コンピューター = computer
• テーブル = table
• スマホ = smartphone

Katakana is often used for:

• foreign loanwords
• onomatopoeia
• emphasis
• some scientific/technical terms

So キーボード in katakana is exactly what you would expect.

In conversation, Japanese often omits information that is clear from context, so yes, sometimes the object could be omitted.

For example, if everyone already knows you are talking about paper, someone might just say:

• キーボードの上に置いてはいけません。

That would mean:

• You must not put it on the keyboard.

However, in the full sentence, 紙を is included because it clearly states what must not be placed there.

No, that would be incorrect here.

You need 紙を because 紙 is the thing someone is placing, so it is the direct object of 置く.

• 紙を置く = put paper

Using が would not fit this structure.

You might see 紙が置いてある in a different sentence:

• キーボードの上に紙が置いてある。
  = There is paper placed on the keyboard.

That sentence describes a state/existence, not a prohibition.

So:

• 紙を置いてはいけません。 = Do not put paper.
• 紙が置いてある。 = Paper has been placed / There is paper placed.