El otorrino observa el tapón de cerumen.

Otorrino is a very common shortened form of otorrinolaringólogo, which means an ear, nose, and throat doctor (an ENT specialist).

In Spain, people often say otorrino in everyday speech because the full word is long. It is completely normal and natural.

• el otorrino = the male ENT doctor / the ENT doctor
• la otorrino or la otorrinolaringóloga = the female ENT doctor

So this sentence uses a very common, everyday medical word.

In Spanish, a singular countable noun usually needs an article or another determiner.

So:

• el otorrino = the ENT doctor
• un otorrino = an ENT doctor

You normally would not just say otorrino observa... on its own.

Also, Spanish often uses the definite article more naturally than English does, especially when talking about people or things already identified by the situation or context.

It can mean either, depending on context.

Observa is the third person singular present tense of observar:

• él observa = he observes / he is observing
• ella observa = she observes / she is observing
• usted observa = you observe / you are observing

Spanish present tense often covers both the English simple present and present continuous, unless the speaker wants to emphasize the ongoing action.

If you really want to stress is observing right now, Spanish could also say:

• está observando

But observa is perfectly normal here.

Because the direct object here is not a person.

Spanish uses the personal a mainly before specific people (and sometimes pets or personified beings):

• Veo al médico. = I see the doctor.
• Veo el tapón. = I see the plug/blockage.

In your sentence:

• observa el tapón de cerumen

That object is a thing, so there is no personal a.

Here, tapón means a plug or blockage.

In a medical context, un tapón de cerumen is an earwax blockage or earwax plug.

The word tapón can also mean:

• a bottle stopper
• a cork
• a traffic jam in some contexts

But here it clearly means a blockage.

Because de + noun is a very common way in Spanish to describe what something is made of, filled with, or caused by.

So:

• tapón de cerumen = plug/blockage of earwax
• more naturally in English: earwax plug / earwax blockage

Using del would usually sound different, as if you meant the plug of the earwax, which is not the normal way to express this idea.

This de structure is very common:

• vaso de agua = glass of water
• mesa de madera = wooden table
• dolor de cabeza = headache

Cerumen is the medical or more formal word for earwax.

In everyday Spanish, people may also say:

• cera = wax
• tapón de cera = earwax blockage

So:

• cerumen sounds more medical/technical
• cera sounds more everyday

In a sentence involving an ENT doctor, cerumen is very natural.

Because tapón is a masculine noun in Spanish, so it takes:

• el tapón
• un tapón

There is no special logical reason you can always predict; grammatical gender is something you generally learn with the noun.

A useful detail here is that tapón ends in -ón, and many nouns with that ending are masculine:

• el corazón
• el pantalón
• el tapón

Not every word follows a simple pattern, but in this case masculine is correct.

De cerumen is a prepositional phrase that modifies tapón.

It tells you what kind of plug/blockage it is:

• el tapón = the plug/blockage
• el tapón de cerumen = the earwax plug/blockage

So the basic structure is:

• El otorrino = subject
• observa = verb
• el tapón de cerumen = direct object

In Spain, otorrino is pronounced roughly:

o-to-RRI-no

A few key points:

• The rr is a strong rolled/trilled r.
• The stress falls on ri: otorRÍno.
• The final o is a clear Spanish vowel sound, not like an English diphthong.

If you cannot trill the rr perfectly yet, that is normal for learners, but it is good to notice that r and rr are different sounds in Spanish.

In standard Spain Spanish, it is roughly:

the-ru-MEN

More precisely:

• ce is pronounced with the th sound used in Spain: the
• the stress is on the last syllable: ceruMEN

In much of Latin America, ce would sound like se, so you would hear:

se-ru-MEN

Both are correct for their varieties; since you are learning Spanish from Spain, the-ru-MEN is the expected pronunciation.

It has an accent mark because the stress falls on the last syllable: ta-PÓN.

In Spanish spelling rules, words ending in n, s, or a vowel are normally stressed on the second-to-last syllable unless there is a written accent.

Without the accent, tapon would be read with the wrong stress. The written accent shows that the correct stress is:

• tapón

Yes, but the meaning and tone change a bit.

• mira = looks at
• observa = observes / examines

Observa sounds more careful, deliberate, and slightly more formal or clinical, which fits a doctor examining something.

So in this medical sentence, observa is a very good choice.

No, this is a very standard Spanish word order:

Subject + verb + direct object

• El otorrino = subject
• observa = verb
• el tapón de cerumen = object

It matches normal English order quite closely:

• The ENT doctor observes the earwax plug.

Spanish can change word order for emphasis, but this version is neutral and natural.