Mi abuelo tiene setenta años.

Because Spanish normally expresses age with tener (to have), not ser or estar.

So:

• Mi abuelo tiene setenta años = literally My grandfather has seventy years
• Natural English: My grandfather is seventy years old

This is one of the biggest differences from English. A sentence like Mi abuelo es setenta años is not correct.

Some more examples:

• Tengo veinte años = I am twenty years old
• Ella tiene cinco años = She is five years old

Tiene is the third-person singular present tense form of tener.

It can mean:

• he has
• she has
• you have (formal usted)

In this sentence, it matches mi abuelo, which is third-person singular.

A few forms of tener in the present tense are:

• yo tengo
• tú tienes
• él/ella/usted tiene
• nosotros tenemos
• ellos/ellas/ustedes tienen

Mi means my. It is a possessive adjective.

Unlike some other Spanish words, mi does not change for gender:

• mi abuelo = my grandfather
• mi abuela = my grandmother

It only changes for number:

• mi abuelo = my grandfather
• mis abuelos = my grandparents / my grandfathers

So mi works with both masculine and feminine singular nouns.

Abuelo is the normal word for grandfather. Depending on context and tone, it can also feel like grandpa.

Related words:

• abuelo = grandfather
• abuela = grandmother
• abuelos = grandparents

If you want a more affectionate or cute form, Spanish often uses:

• abuelito = grandpa / dear grandpa
• abuelita = grandma / dear grandma

So abuelo is neutral and very common.

Because in Spanish, a possessive like mi usually replaces the article.

So Spanish says:

• mi abuelo

Not:

• el mi abuelo in modern standard Spanish

This is different from English only in structure, not meaning. The possessive already does the job.

Usually, yes. The standard full expression is:

• tener + number + años

So:

• Mi abuelo tiene setenta años

In casual conversation, native speakers may sometimes shorten it if the context is obvious:

• Mi abuelo tiene setenta

But for learners, the safest and most natural full form is to include años.

No. Setenta does not change.

You use the same form with masculine, feminine, singular, and plural nouns:

• setenta años
• setenta personas
• setenta casas

Many Spanish numbers work like this. So once you know setenta, you can use it in many contexts without changing it.

Spanish often allows the subject to be omitted if it is clear from context.

So you can say:

• Tiene setenta años

But there is an important detail: tiene could mean:

• he has
• she has
• you have (formal)

So if the context does not make it clear, keeping mi abuelo helps.

The full sentence is the clearest version:

• Mi abuelo tiene setenta años

The ñ is a separate Spanish letter, not just an n with an accent mark.

It is pronounced roughly like the ny sound in canyon.

So:

• años sounds roughly like AHN-yos

A simple pronunciation guide for the whole sentence is:

• mee ah-BWEH-loh TYEH-neh seh-TEN-tah AHN-yos

A few notes:

• abuelo is stressed on bue
• tiene starts with a sound like tyeh
• setenta is stressed on ten
• años has the ñ sound, not a regular n

The normal, neutral order is:

• Mi abuelo tiene setenta años

That is the most natural way to say it in most situations.

Spanish can sometimes change word order for emphasis or style, but learners should stick with the standard pattern:

• subject + verb + age expression

For example:

• Mi abuela tiene ochenta años
• Mi hermano tiene diez años

Yes. It is in the present indicative.

That is the normal tense to use for someone’s current age:

• Mi abuelo tiene setenta años = my grandfather is seventy years old

If you wanted a past age, you would change the tense:

• Mi abuelo tenía setenta años = my grandfather was seventy years old / used to be seventy years old

So the sentence as written refers to his age now.

Yes. This is a very common pattern in Spanish:

• [person] + tener + [number] + años

Examples:

• Yo tengo treinta años
• Mi madre tiene cincuenta años
• Ellos tienen doce años
• ¿Cuántos años tienes?

Once you learn this pattern, you can use it for almost anyone.