Prima di bere il caffè caldo, metto un cucchiaino di zucchero.

Because prima di + infinitive is the normal structure when the subject is the same in both parts of the sentence.

• Prima di bere il caffè caldo, metto... = Before drinking the hot coffee, I put...

The person who drinks the coffee and the person who puts in the sugar is the same person: I.

You usually use prima che + verb when the subject changes:

• Metto lo zucchero prima che lui beva il caffè. = I add sugar before he drinks the coffee.

So in your sentence, prima di bere is exactly what you would expect.

After prima di, Italian normally uses the infinitive when there is no subject change.

So:

• prima di bere = before drinking
• prima di mangiare = before eating
• prima di uscire = before going out

This works a lot like English before + -ing in meaning, even though the grammar is different.

Italian uses articles much more often than English.

So where English might say:

• Before drinking hot coffee...

Italian very naturally says:

• Prima di bere il caffè caldo...

Here il caffè can refer to the coffee in question, the coffee you are about to drink, or simply coffee in a more concrete way than English usually does.

This is very normal in Italian. English often drops the article where Italian keeps it.

In this sentence, caldo most naturally means hot.

So:

• il caffè caldo = the hot coffee

Depending on context, caldo can sometimes cover a range from warm to hot, but with coffee it is usually understood as hot.

In Italian, adjectives often come after the noun.

So:

• il caffè caldo = the hot coffee
• una casa grande = a big house
• un libro interessante = an interesting book

Some adjectives can come before the noun, but the most basic and neutral position for many descriptive adjectives is after the noun.

So il caffè caldo is the normal order.

Metto is the first person singular present tense of mettere.

• mettere = to put
• metto = I put / I add / I place

In this sentence, metto un cucchiaino di zucchero is best understood as:

• I add a teaspoon of sugar

Italian often uses mettere in places where English might prefer add.

Because Italian usually drops subject pronouns when they are not needed.

• metto already tells you the subject is I
• metti = you put
• mette = he/she/it puts

So metto by itself already means I put or I add.

You could say io metto, but that would usually add emphasis, contrast, or clarity:

• Io metto lo zucchero, lui no. = I add sugar, he doesn’t.

Here it means a teaspoon of sugar, meaning a small spoonful / teaspoon amount.

Cucchiaino literally means small spoon or teaspoon, but in everyday use it often refers to the teaspoon as a measure too.

So:

• un cucchiaino di zucchero = a teaspoon of sugar

This is a very natural way to say it in Italian.

• cucchiaino = teaspoon / small spoon
• cucchiaio = tablespoon / spoon

So if you want a small spoon used for coffee or tea, cucchiaino is the right word.

Examples:

• un cucchiaino di zucchero = a teaspoon of sugar
• un cucchiaio di zucchero = a tablespoon of sugar

Because the two di phrases do different jobs.

1. prima di bere

   • Here di is part of the expression prima di + infinitive
   • It means before doing something

2. un cucchiaino di zucchero

   • Here di means of
   • It shows what the teaspoon contains or measures

So even though the same word appears twice, the grammar is different in each case.

The comma separates the introductory time phrase from the main clause.

• Prima di bere il caffè caldo, metto un cucchiaino di zucchero.

The first part tells when:

• Prima di bere il caffè caldo = before drinking the hot coffee

The second part gives the main action:

• metto un cucchiaino di zucchero = I add a teaspoon of sugar

In Italian, this comma is very natural and helpful. In short sentences, punctuation can sometimes vary, but here the comma is standard and clear.

Yes. You could also say:

• Metto un cucchiaino di zucchero prima di bere il caffè caldo.

This means the same thing.

The version with prima di bere... first puts the time/background information first, while the version with metto... first focuses more immediately on the action.

Both are correct.

Here caffè is singular:

• il caffè = the coffee

It has a written accent because the stress falls on the last syllable:

• caf-FÈ

The accent is part of the standard spelling:

• caffè = coffee

The plural is often the same in form when it means cups of coffee in certain contexts, but in this sentence you should simply read il caffè as singular.

Yes, that is a possible nuance.

Most directly, il caffè caldo means the hot coffee. So the sentence naturally means:

• Before drinking the hot coffee, I add a teaspoon of sugar.

But in real life, this also often implies drinking it while it is still hot. That nuance comes from the situation more than from special grammar.

So the core grammar is simply:

• caffè = coffee
• caldo = hot

Most naturally, it sounds like a habit or a general routine, because Italian often uses the present tense for habitual actions.

• Prima di bere il caffè caldo, metto un cucchiaino di zucchero. = Before drinking hot coffee / my hot coffee, I add a teaspoon of sugar.

Depending on context, it could also describe what someone is doing right now, but without extra context it sounds very much like a regular habit.