Mi amigo estadounidense habla español.

Because mi is the possessive form used before a noun.

• mi amigo = my friend
• mi casa = my house

Mío is used differently. It usually appears:

• on its own: Es mío = It is mine
• or after a noun: un amigo mío = a friend of mine

So mío amigo is not correct in standard Spanish.

Amigo is masculine, so it refers to a male friend. If the friend were female, you would say:

Mi amiga estadounidense habla español.

So the noun changes according to the person’s gender:

• amigo = male friend
• amiga = female friend

In Spanish, descriptive adjectives like nationality words usually come after the noun.

So:

• amigo estadounidense = American friend
• coche español = Spanish car

This is the normal word order in Spanish. Putting estadounidense before amigo would sound unusual or very marked in ordinary speech.

In Spain, estadounidense is the most precise and standard way to say from the United States.

That is because americano can also refer more broadly to the Americas, not just the USA. In casual speech, some people do say americano, but estadounidense is clearer and often preferred, especially in careful or neutral Spanish.

No. Estadounidense has the same form for both masculine and feminine singular.

• mi amigo estadounidense
• mi amiga estadounidense

Only the plural changes:

• mis amigos estadounidenses
• mis amigas estadounidenses

So unlike adjectives such as español / española, estadounidense does not change for gender.

Because habla is the third-person singular present form of hablar, and it matches the subject mi amigo.

Present tense of hablar:

• yo hablo
• tú hablas
• él / ella / usted habla
• nosotros hablamos
• vosotros habláis
• ellos / ellas / ustedes hablan

Since mi amigo = he / my friend, the correct form is habla.

Spanish often leaves out subject pronouns when they are not necessary.

So instead of saying:

Él habla español.

Spanish very often just says:

Habla español.

The verb ending already tells you the subject is he/she/you formal in the singular, and here mi amigo already makes the subject clear. Adding él is possible, but it would usually be for emphasis, contrast, or clarity.

After the verb hablar, languages are usually used without an article.

So you say:

• Habla español
• Hablo inglés
• Hablan francés

Not normally:

• Habla el español ❌

You may see el español in other contexts, for example when talking about the language itself in a general or specific way:

• El español es una lengua romance.
• Estudia el español del siglo XVII.

But after hablar, no article is normally used.

Because in Spanish, names of languages and nationalities are normally not capitalized.

So Spanish writes:

• español
• inglés
• francés
• estadounidense

This is different from English, where Spanish and American are capitalized.

The ñ is a separate Spanish letter. It sounds roughly like the ny in canyon.

So español is pronounced approximately like:

es-pan-YOL

The stress is on the last syllable: -ñol.

A rough pronunciation guide for the full sentence could be:

Mee ah-MEE-go eh-stah-doh-oo-nee-DEN-seh AH-blah es-pan-YOL

That is only an approximation, but it helps an English speaker get close.

Yes, you could. It means the same thing and is completely understandable.

• Mi amigo estadounidense habla español.
• Mi amigo de Estados Unidos habla español.

The first one is more compact and sounds like a straightforward nationality adjective. The second is a little more literal: my friend from the United States. Both are correct.