Mi amigo es mexicano.

Mi is the possessive adjective used directly before a noun: mi amigo = my friend.

Mío is a possessive pronoun/adjective form used in other structures, such as:

• El amigo es mío = The friend is mine
• Un amigo mío = a friend of mine

So before the noun amigo, you use mi.

Spanish has two verbs for to be: ser and estar.

Here, es comes from ser, which is used for:

• identity
• origin
• nationality
• permanent or defining characteristics

Since mexicano expresses nationality, Spanish uses ser:

• Mi amigo es mexicano.

You would not normally say está mexicano for nationality.

In Spanish, nationalities and languages are not capitalized unless they begin a sentence.

So:

• mexicano
• español
• inglés

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

Yes, amigo is grammatically masculine and usually refers to a male friend.

For a female friend, you would say:

• Mi amiga es mexicana.

Notice that both the noun and the nationality adjective change:

• amigo → amiga
• mexicano → mexicana

In Spanish, adjectives often agree with the noun they describe in gender and number.

Since amigo is masculine singular, the adjective is also masculine singular:

• amigo mexicano

If the noun were feminine:

• amiga mexicana

If plural:

• amigos mexicanos
• amigas mexicanas

No. México is the country, while mexicano is the nationality adjective/noun.

So:

• México = Mexico
• mexicano = Mexican

To talk about nationality, use mexicano, not México.

In English, we often say He is a doctor or He is an American. In Spanish, when someone’s profession, religion, or nationality comes after ser, the article is often omitted.

So Spanish says:

• Es mexicano not
• Es un mexicano in this basic descriptive sense

Using un can sometimes change the tone or emphasis, so learners should usually stick with es mexicano for simple nationality statements.

A simple Latin American pronunciation guide:

• Mi ≈ mee
• amigo ≈ ah-MEE-go
• es ≈ ess
• mexicano ≈ meh-hee-KAH-no in many parts of Latin America, because the x in México/mexicano is pronounced like a strong h sound

A rough full pronunciation:

• mee ah-MEE-go ess meh-hee-KAH-no

Depending on region, pronunciation details can vary a little.

Yes.

In Mi amigo es mexicano, mexicano is functioning like an adjective describing your friend’s nationality.

But it can also be used as a noun:

• Él es mexicano. = He is Mexican.
• Los mexicanos son... = Mexicans are...

Spanish often allows nationality words to work both ways.

Yes. That means My friend is from Mexico.

These are closely related but not identical:

• Es mexicano = he is Mexican
• Es de México = he is from Mexico

Often both are true, but grammatically they express different ideas:

• nationality → mexicano
• place of origin → de México

This is the most neutral and natural word order in Spanish:

• Mi amigo = subject
• es = verb
• mexicano = complement

Spanish word order is somewhat flexible, but this standard order is the best choice for learners. Other orders may sound more emphatic or literary depending on context.

You would make the noun, verb, and adjective plural:

• Mis amigos son mexicanos.

Changes:

• mi → mis
• amigo → amigos
• es → son
• mexicano → mexicanos

If they are all female:

• Mis amigas son mexicanas.