Я положил удлинитель под стол, чтобы провод не мешал.

Положил is the perfective past form of положить, meaning put / placed as a completed action.

So:

• Я положил удлинитель под стол = I put the extension cord under the table (and the action is completed)

If you used клал (from класть), it would be imperfective, which usually suggests:

• a repeated action,
• an ongoing process,
• or focus on the action itself rather than the result.

In this sentence, the speaker is talking about a single finished act, so положил is the natural choice.

Удлинитель usually means an extension cord or extension lead. In everyday Russian, it can refer to:

• a simple extension cord,
• or sometimes a power strip, depending on context.

So the word is slightly broader than one exact English term. In this sentence, it simply means some kind of electrical extension lead/cable setup placed under the table.

This is a very common Russian case pattern with prepositions like под.

• под + accusative = movement to a position under something
• под + instrumental = location under something

So:

• Я положил удлинитель под стол = I put the extension cord under the table
  (movement to that place)

But:

• Удлинитель лежит под столом = The extension cord is under the table
  (static location)

Since положил involves placing something somewhere, Russian uses под стол.

Чтобы introduces a purpose clause. It often means:

• so that
• in order that
• sometimes just so

So the whole sentence means:

• I put the extension cord under the table so that the wire wouldn’t be in the way.

This is one of the most common uses of чтобы in Russian.

This is a very common point of confusion.

After чтобы, Russian often uses a form that looks like the past tense, but it does not necessarily mean real past time. In purpose clauses, this form is normal.

So:

• чтобы провод не мешал = so that the wire wouldn’t be in the way / so that the wire doesn’t get in the way

Even though мешал looks past-tense, here it is part of the standard structure after чтобы.

You should think of чтобы + past-form verb as a grammar pattern, not as literal past time.

Мешал agrees with провод.

• провод = masculine singular
• so the verb form is masculine singular: мешал

Compare:

• чтобы провод не мешал = so that the wire wouldn’t be in the way
• чтобы лампа не мешала = so that the lamp wouldn’t be in the way
• чтобы провода не мешали = so that the wires wouldn’t be in the way

So the ending depends on the subject of the subordinate clause.

Мешать often means:

• to bother
• to hinder
• to interfere
• to get in the way

In this sentence, the most natural English meaning is:

• to be in the way
• to get in the way

So чтобы провод не мешал means the wire/cable would not be obstructing anyone or anything.

If you want to make the person explicit, Russian often uses the dative:

• чтобы провод мне не мешал = so that the wire wouldn’t get in my way

In your sentence, that person is just left unstated.

Both words can relate to wires/cables, but they are not always used in exactly the same way.

• провод often means wire or cord
• кабель often sounds more like cable, sometimes a bit more technical or heavier-duty

In everyday speech, провод is very natural when talking about the cord trailing from an appliance or extension lead and getting in the way.

So here провод sounds normal and idiomatic.

Yes. In the second clause, the subject is провод.

Structure:

• Я положил удлинитель под стол
• чтобы провод не мешал

So the idea is:

• I put the extension cord under the table
• so that the wire/cord would not be in the way

Even though удлинитель is the main object in the first clause, the second clause has its own subject: провод.

Yes, you could, but the word order changes the feel.

• чтобы провод не мешал = the most neutral order
• чтобы не мешал провод = more marked; it can sound more emphatic or stylistically shaped

Russian word order is flexible, but the neutral version here is чтобы провод не мешал.

For a learner, that is the safest version to use.

Russian often leaves pronouns out when the meaning is already clear.

Here, instead of saying something like:

• чтобы он не мешал

the speaker uses the noun itself:

• чтобы провод не мешал

That is clearer and very natural. Russian generally avoids unnecessary pronouns more than English does.

Literally, the first clause says:

• I put the extension cord under the table

The second clause then mentions the wire/cable as the thing that should not be in the way.

In real life, that suggests the speaker put the extension lead underneath so that its cord would not stick out and bother anyone. So the sentence is perfectly natural even though it mentions удлинитель first and провод second.

Russian does not have articles like a/an/the.

So:

• под стол can mean under a table or under the table
• провод can mean a wire or the wire

The exact meaning comes from context. In this sentence, English would naturally use the table and the wire, but Russian does not need separate words for that.

Yes, in everyday speech they can refer to closely related parts of the same setup.

• удлинитель = the extension lead/device as a whole
• провод = the wire/cord part of it

So the sentence is not contradictory. It is saying the speaker placed the extension lead under the table so that the cord would not be in the way.

Yes, it sounds natural.

It has very normal everyday vocabulary:

• Я положил... = I put...
• под стол = under the table
• чтобы... не мешал = so that ... wouldn’t get in the way

A native speaker would understand it immediately. It sounds like an ordinary practical comment about arranging cables in a room.