Eu deixo meu casaco em outro cabide no armário.

In Portuguese, the subject pronoun is often optional because the verb ending already shows who is doing the action. So:

• deixo already means I leave / I put / I keep
• eu deixo adds emphasis, clarity, or contrast

This sentence could also be simply:

• Deixo meu casaco em outro cabide no armário.

Both are natural. Using eu is not wrong at all; it just makes the subject more explicit.

Deixar is the infinitive, meaning to leave, to let, or sometimes to put/keep depending on context.

In the sentence, you need the conjugated form to match eu:

• deixar = to leave
• eu deixo = I leave / I put

So deixo is the first person singular present tense form of deixar.

Here, deixar means something like to leave or to put and leave somewhere.

So in this sentence, it does not mean to let someone do something. It means that the speaker places the coat somewhere and leaves it there.

Depending on context, deixar can mean different things:

• deixar algo em algum lugar = to leave something somewhere
• deixar alguém fazer algo = to let someone do something

In your sentence, it is the first meaning.

In Brazilian Portuguese, both are possible:

• meu casaco
• o meu casaco

Portuguese often allows a definite article before possessives, but in Brazil it is very common to omit it, especially in everyday speech.

So:

• meu casaco = my coat
• o meu casaco = my coat

There is usually little or no difference in meaning here. The version without the article sounds very normal and natural.

Portuguese often does not need an indefinite article in places where English uses a/an.

So:

• em outro cabide = on another hanger

You could also say:

• em um outro cabide

That is also possible, but em outro cabide is perfectly natural and a bit leaner.

The word outro already gives a kind of indefinite meaning, so adding um is often unnecessary.

Both are location phrases, but they work a little differently.

• em outro cabide = on/in another hanger
• no armário = in the wardrobe/closet

no is a contraction of:

• em + o = no

So:

• no armário literally means in the closet/wardrobe

The sentence describes a more specific location inside a larger one:

• the coat is on another hanger
• that hanger is in the wardrobe

Because armário here has a definite article:

• o armário = the wardrobe / the closet

When em comes before o, they combine:

• em + o = no

So:

• no armário = in the wardrobe / in the closet

If it were indefinite, you might see:

• em um armário = in a wardrobe / in a closet

Logically, it describes the whole situation, but most naturally it is understood as describing the location of the hanger:

• the coat is left on another hanger
• that hanger is in the closet

So the image is: the coat is hanging on another hanger inside the wardrobe.

This is a normal and natural way to stack location phrases in Portuguese.

Yes, you could, but the meaning shifts slightly.

• deixo suggests I leave it there / I keep it there / I place it there and it remains there
• coloco focuses more directly on the act of putting/placing

So:

• Eu deixo meu casaco... = I leave my coat...
• Eu coloco meu casaco... = I put my coat...

Both can work, but deixo emphasizes the resulting state a little more.

Cabide means hanger, especially a clothes hanger.

So:

• casaco = coat
• cabide = hanger
• armário = wardrobe / closet

In this sentence, outro cabide means another hanger, probably a different hanger from the usual one or from the one mentioned before.

That is the normal position. In Portuguese, outro usually comes before the noun:

• outro cabide = another hanger
• outra camisa = another shirt

This is just standard word order.

The present tense in Portuguese can do both, depending on context.

• Eu deixo meu casaco em outro cabide no armário can mean a habitual action: I leave my coat on another hanger in the closet
• It can also describe what someone does in a present situation, depending on the conversation

Without extra context, many learners should understand it first as a general or habitual statement.

Yes. Prepositions do not always match exactly between English and Portuguese.

Portuguese commonly uses em in many location expressions where English might use in, on, or at depending on the noun.

So even though English says on a hanger, Portuguese can naturally say:

• em um cabide
• em outro cabide

This is normal Portuguese usage, not a mistake.