Il freno a disco ferma il rotore.

Because both freno and rotore are singular masculine nouns, and in this sentence they are both definite: the brake and the rotor.

• il freno = the brake
• il rotore = the rotor

Italian usually uses the definite article more regularly than English, so seeing il twice is completely normal.

Italian has different forms of the depending on the sound that follows.

Use il before most singular masculine nouns beginning with a normal consonant:

• il freno
• il rotore

You would use lo before masculine singular nouns beginning with:

• s
  • consonant, as in lo sport
• z, as in lo zaino
• ps, gn, x, y, and a few similar cases

So freno and rotore take il, not lo.

A disco is part of the fixed expression freno a disco, meaning disc brake.

In Italian, a can be used in expressions that describe type, function, or design. So freno a disco literally looks like brake with a disc / disc-type brake.

This is similar to other patterns in Italian such as:

• barca a vela = sailboat
• fornello a gas = gas stove
• macchina a vapore = steam engine

So here a disco is not a location phrase like to the disc. It is describing what kind of brake it is.

Because disco here is not a specific object being introduced as the disc. It is part of a classification: a disc brake, not a brake to the disc.

• a disco = disc-type / with disc
• al disco = to the disc / at the disc

So freno a disco is a standard compound expression, and adding the article would change the meaning.

The verb agrees with the subject, which is il freno a disco. That subject is:

• third person
• singular

So the verb form is ferma = stops

This comes from the verb fermare.

Present tense:

• io fermo = I stop
• tu fermi = you stop
• lui/lei ferma = he/she/it stops
• noi fermiamo = we stop
• voi fermate = you all stop
• loro fermano = they stop

Since il freno a disco is it, Italian uses ferma.

In this sentence, the normal Italian word order helps:

• Il freno a disco = subject
• ferma = verb
• il rotore = direct object

So the structure is:

Subject + Verb + Object

This is the same basic order as English in a simple sentence.

Also, the meaning of the verb supports it:

• the brake does the action
• the rotor receives the action

Yes, Italian can sometimes change word order for emphasis, but the standard neutral order here is:

Il freno a disco ferma il rotore.

That is the most natural version for a plain statement.

A changed order might be possible in a special context, but for learners, the safest pattern is:

• subject first
• verb second
• object after the verb

Both nouns here are masculine singular:

• il freno → plural i freni
• il rotore → plural i rotori

So if you wanted to make the whole sentence plural, you could say:

I freni a disco fermano i rotori.

Notice the changes:

• il → i
• freno → freni
• ferma → fermano
• rotore → rotori

In Italian, the simple present can often translate into English in more than one way, depending on context.

So ferma can mean:

• stops
• is stopping

In a general or technical statement like this one, English usually prefers stops:

• The disc brake stops the rotor.

Italian normally does not use an auxiliary like English do/does for ordinary present-tense statements.

English:

• The brake stops the rotor.
• The brake does stop the rotor. ← emphatic

Italian usually just uses the main verb:

• Il freno a disco ferma il rotore.

If you want emphasis in Italian, you usually show it through context, stress, or wording, not by adding a direct equivalent of English does.

A simple approximate pronunciation is:

• il = eel
• freno = FREH-no
• a = ah
• disco = DEE-sko
• ferma = FEHR-ma
• rotore = ro-TO-re

A few useful notes:

• Italian r is usually tapped or lightly rolled
• e and o are clear vowels, not reduced like in English
• sc in disco is just a hard sk sound

So the whole sentence sounds approximately like:

eel FREH-no ah DEE-sko FEHR-ma eel ro-TO-re