El cerebro controla el cuerpo.

Because both are singular, masculine nouns, and in Spanish common nouns usually need an article when you are talking about the thing in general or a specific thing.

• el cerebro = the brain
• el cuerpo = the body

Spanish uses articles more often than English does, especially with body parts and general statements.

They are masculine because that is their grammatical gender, so they take el in the singular:

• el cerebro
• el cuerpo

There is no perfect rule, but many nouns ending in -o are masculine. That pattern works here.

Controlar is the infinitive, meaning to control. In a full sentence, Spanish usually uses a conjugated verb.

Here, controla is the third-person singular present tense form of controlar:

• yo controlo = I control
• tú controlas = you control
• él / ella / usted controla = he / she / you control(s)

Since el cerebro is he/it grammatically, the sentence uses controla.

Spanish often leaves out subject pronouns because the verb ending already shows who is doing the action.

Here, controla could mean he/she/it controls, but the noun el cerebro is already there, so adding él would be unnecessary.

Spanish prefers:

• El cerebro controla el cuerpo.

Not usually:

• Él controla el cuerpo.
  unless the speaker specifically wants to emphasize he/it.

Usually it means controls.

The Spanish present tense can sometimes match both English simple present and present continuous, depending on context. But in a general fact like this one, controla is best understood as:

• The brain controls the body.

If you specifically wanted is controlling right now, Spanish would more likely use:

• está controlando

But that would sound odd here because this sentence is a general truth.

With body parts, Spanish often uses the definite article (el, la, los, las) where English uses a possessive like my, your, his, its.

So Spanish commonly says:

• el cuerpo = literally the body

even when English would naturally say:

• its body
• his body
• her body

In this sentence, el cuerpo sounds natural in Spanish.

Yes, but El cerebro controla el cuerpo is the most normal and neutral order.

This is the standard pattern:

• Subject + Verb + Object

So:

• El cerebro = subject
• controla = verb
• el cuerpo = object

Other word orders are possible in Spanish, but they usually sound marked, poetic, or emphasize something.

In Spain, cerebro is pronounced approximately theh-REH-bro.

A few helpful points:

• The first c before e is pronounced like the th in thin in standard Peninsular Spanish.
• The r in cerebro is a light tap.
• Stress is on the middle syllable: ce-RE-bro

So in Spain:

• cerebro ≈ theh-REH-bro

Approximately kon-TRO-la.

A few notes:

• The c here is before o, so it sounds like a normal k sound.
• The stress is on tro: con-TRO-la
• The r is a single tapped r

It is most naturally understood as a general truth: the brain controls the body.

Spanish often uses the singular definite article for general statements:

• El cerebro controla el cuerpo.

This can mean something like:

• The brain controls the body
• Brains control bodies, as a general biological fact

So even though the sentence is singular, it can still express a general idea.