Este corredor trota tan rápido como su amigo.

Este means this and is used for a masculine singular noun, here corredor.

• este corredor = this runner
• ese corredor = that runner
• aquel corredor = that runner over there

Spanish distinguishes these demonstratives more clearly than English often does.

Because corredor is the masculine singular form.

• el corredor = the male runner
• la corredora = the female runner

So if you were talking about a woman, you would say:

Esta corredora trota tan rápido como su amiga.

The adjective and demonstrative would also change to match.

Because the sentence does not mean This runner is jogging... It means This runner jogs / is jogging...

In Spanish, the simple present trota can often translate as either:

• jogs
• is jogging

depending on context.

So trota already contains the subject and the verb idea. No separate is is needed.

Trota is the third-person singular present tense of trotar.

Conjugation:

• yo troto = I jog
• tú trotas = you jog
• él / ella trota = he / she jogs

Since the subject is este corredor (a singular third-person subject), trota is the correct form.

Because trotar and correr are related but not identical.

• trotar = to jog, to trot
• correr = to run

So trota suggests a jogging pace rather than full running. If the sentence used corre, the meaning would shift to runs rather than jogs.

This is the standard Spanish structure for as ... as comparisons with adjectives or adverbs:

tan + adjective/adverb + como

So:

• tan rápido como = as fast as

Other examples:

• tan alto como = as tall as
• tan lentamente como = as slowly as
• tan interesante como = as interesting as

This is different from comparisons of quantity, where Spanish uses tanto/a/os/as ... como.

Because in Spanish, some adjectives are commonly used adverbially after verbs of movement.

So:

• trota rápido = jogs fast
• corre rápido = runs fast

This is very natural Spanish.

You can also say rápidamente, but it often sounds a bit more formal or emphatic:

• trota rápidamente

In everyday speech, rápido is extremely common.

Because here rápido is functioning like an adverb, describing how he jogs, not describing the noun corredor directly.

Compare:

• Este corredor es rápido.
  Here rápido is an adjective describing the runner, so it agrees with the noun.

• Este corredor trota rápido.
  Here rápido describes the action trota, so it works adverbially and does not change.

That is why rápido stays the same in this sentence.

Here como means as, and it completes the comparison started by tan.

So:

• tan rápido como su amigo = as fast as his friend

Do not confuse this with other uses of como, such as:

• como = I eat / like I eat (from comer) in some contexts
• como = like / as
• ¿cómo? = how?

In this sentence, it is the comparison word as.

Yes. Su amigo can mean:

• his friend
• her friend
• your friend (formal singular)
• their friend

Spanish su is less specific than English his/her/their.

In this sentence, context usually tells you whose friend it is. If needed, Spanish can make it clearer:

• el amigo de él = his friend
• el amigo de ella = her friend

But normally su amigo is perfectly natural.

Because su amigo is the normal possessive structure for his/her/their friend.

• su amigo = his/her/their friend

You only use de in a different structure, for example:

• el amigo de Juan = Juan’s friend
• el amigo de él = his friend

So in this sentence, su amigo is the simplest and most natural option.

Spanish usually does not use an article before a possessive adjective like mi, tu, su, nuestro.

So:

• su amigo = his friend
• not el su amigo

This is the normal pattern in Spanish.

The given order is the most natural neutral order:

Este corredor trota tan rápido como su amigo.

Spanish word order is somewhat flexible, but not all rearrangements sound equally natural.

For example, you could say:

• Este corredor trota tan rápido como su amigo.
  normal, neutral

You generally would not move the comparison phrase around unless you had a special reason for emphasis. For learners, it is best to keep this standard order.

You would change the words that must agree with a feminine noun:

• Este → Esta
• corredor → corredora

So:

Esta corredora trota tan rápido como su amiga.

If the friend is also female, amigo becomes amiga. If the friend is male, it stays amigo.

A simple pronunciation guide:

• Este ≈ ES-te
• corredor ≈ ko-rre-DOR
• trota ≈ TRO-ta
• tan ≈ tan
• rápido ≈ RA-pi-do
• como ≈ KO-mo
• su amigo ≈ su a-MI-go

A Spain pronunciation note:

• c before o in como sounds like a normal k
• r in rápido is a tapped Spanish r
• rr in corredor is a stronger rolled sound

Stress falls on:

• correDOR
• RÁpido
• aMIgo