El té se enfría rápido cuando hablo demasiado.

Because enfriarse is the common verb for to get cold / to cool down by itself.

• El té se enfría = The tea cools down
• Alguien enfría el té = Someone cools the tea down

So in this sentence, the tea is changing state on its own, which is why Spanish uses se.

This se is not really himself/itself in the English sense. It is part of the verb enfriarse.

Not here. It is better understood as a pronominal / change-of-state use, not a true passive.

• El té se enfría = The tea gets cold / cools down
• Passive would be more like El té es enfriado..., but that sounds unnatural here

So the sentence is describing what happens to the tea, not focusing on an external agent.

Because Spanish usually drops subject pronouns when the verb ending already makes the subject clear.

• hablo = I speak / I talk
• The -o ending already tells you the subject is yo

So:

• cuando hablo demasiado = when I talk too much

Adding yo is possible, but it would usually be for emphasis or contrast:

• cuando yo hablo demasiado = when I talk too much (with extra emphasis on I)

Because this sentence expresses a habitual or general situation.

• cuando hablo demasiado = when I talk too much
• It means whenever or when that happens

Spanish often uses the present tense for general truths or repeated situations, just like English does.

If you changed the tense, the meaning would change:

• cuando hablé demasiado = when I talked too much (a specific past event)
• cuando hable demasiado = when I talk too much / if I talk too much in some future-oriented contexts

But in your sentence, the plain present is the natural choice.

Both are possible, but rápido is very common and natural in everyday Spanish.

• se enfría rápido
• se enfría rápidamente

Both mean it cools down quickly.

Using an adjective as an adverb like this is very common in spoken Spanish. Rápido sounds a bit more everyday and direct; rápidamente sounds a bit more formal or heavier.

Because here demasiado is working as an adverb, not an adjective.

It modifies the verb hablo:

• hablo demasiado = I talk too much

As an adverb, demasiado does not agree with anything.

Compare:

• Hablo demasiado = I talk too much → adverb
• Tengo demasiados libros = I have too many books → adjective, so it agrees with libros

The accent mark distinguishes té (tea) from te (you, object pronoun).

• té = tea
• te = you

Examples:

• El té está caliente = The tea is hot
• Te veo = I see you

So the accent is important because it changes the meaning.

Spanish often uses the definite article more than English does.

Here el té can mean:

• the tea (a specific tea in the situation), or
• tea in a general, familiar sense depending on context

In this sentence, el té sounds natural because it refers to the tea being drunk at that moment, or to tea as the thing being discussed.

Saying just té here would not sound natural.

Yes. The most natural place here is after the verb phrase:

• El té se enfría rápido cuando hablo demasiado.

But Spanish allows some flexibility:

• El té rápido se enfría... → unnatural here
• Cuando hablo demasiado, el té se enfría rápido. → very natural

So the adverb is flexible, but not every position sounds equally natural.

In this sentence, cuando is best understood as when / whenever.

Because the sentence is about a repeated situation, English could express it either way:

• The tea cools down quickly when I talk too much
• The tea cools down quickly whenever I talk too much

So cuando can cover both ideas depending on context.

Not if you want the same meaning.

• El té está frío = The tea is cold
• El té se enfría = The tea is getting cold / cooling down

So:

• está frío describes a state
• se enfría describes a process or change

Your sentence is about the tea becoming cold while the speaker talks, so se enfría is the right choice.

Yes. In this sentence, hablo demasiado can be translated as either:

• I talk too much
• I speak too much

In natural English, talk too much is the more idiomatic choice here. But grammatically, hablar covers both ideas.

A natural pronunciation in standard Peninsular Spanish would be roughly:

el TE se en-FREE-a RRA-pee-do KWAN-do A-blo de-ma-SYA-do

A few useful details:

• té has stress on the only syllable
• enfría has stress on -frí-
• hablo has a silent h
• in much of Spain, z and soft c are pronounced with a th sound, but there is no z or soft c in this sentence
• r in rápido is tapped, and rr is not used here

If you want to sound natural, the key stress points are:

• té
• frí
• rá
• cuan
• ha
• sia in demasiado