Der Bremsbelag ist nicht neu.

Because Bremsbelag is a masculine noun in German, so its nominative singular article is der.

A useful rule with German compound nouns is that the last part decides the gender. Here the last part is Belag, and Belag is masculine, so the whole compound is masculine too:

• der Belag
• der Bremsbelag

So in this sentence, der is the correct article.

It is in the nominative case because it is the subject of the sentence.

You can identify the subject by asking: What is not new?
Answer: Der Bremsbelag.

So the structure is:

• Der Bremsbelag = subject, nominative
• ist = verb
• nicht neu = predicate description

German very often forms nouns by combining smaller nouns or word stems into one compound noun.

Here:

• Brems- comes from Bremse = brake
• Belag = lining, coating, pad, covering

Together, Bremsbelag is a single compound noun. This is completely normal in German.

A very important point: in German, compounds are usually written as one word, not as separate words like in English.

Because German main clauses normally follow the verb-second rule (V2 word order).

In a simple statement, the finite verb goes in the second position:

• Der Bremsbelag | ist | nicht neu

Even if you begin with something else, the verb still stays second:

• Heute ist der Bremsbelag nicht neu.
• Zum Glück ist der Bremsbelag nicht neu.

So ist is in the correct place for a normal German statement.

Use nicht because you are negating the adjective/predicate neu, not a noun.

This sentence means:

• The brake pad is not new.

Here, neu is being negated, so German uses nicht.

Use kein when you negate a noun with an indefinite idea, like no / not a:

• Das ist kein Bremsbelag. = That is not a brake pad.
• Der Bremsbelag ist nicht neu. = The brake pad is not new.

So:

• kein negates nouns
• nicht negates adjectives, verbs, whole clauses, or specific parts of a sentence

Because nicht is negating the adjective neu.

In sentences with sein + adjective, German usually places nicht directly before the adjective being negated:

• ist nicht neu
• ist nicht teuer
• ist nicht gut

So nicht neu works like not new in English.

If you put nicht somewhere else, the emphasis can change, and in this short sentence ist nicht neu is the natural standard order.

Because neu is a predicate adjective, not an adjective directly in front of a noun.

Compare:

• der neue Bremsbelag = new brake pad
  
  • here neu comes before the noun, so it takes an ending: neue
• der Bremsbelag ist neu = the brake pad is new
  
  • here neu comes after ist, so it does not take an ending

This is a very common pattern in German:

• Das Auto ist schnell.
• Die Schuhe sind teuer.
• Der Bremsbelag ist neu.

Predicate adjectives stay in their basic form.

No, that is not normal German word order.

The natural form is:

• Der Bremsbelag ist nicht neu.

In German, nicht usually comes before the word or phrase it negates. Since it negates neu, it goes before neu.

So neu nicht sounds wrong here.

The plural would be:

• Die Bremsbeläge sind nicht neu.

Changes:

• der → die for plural
• Bremsbelag → Bremsbeläge
• ist → sind

So if you are talking about more than one brake pad, that is the form you would use.

A helpful approximate pronunciation is:

• Bremsbelag ≈ BREMSS-buh-lahk

A few points:

• Brems- sounds like brehms
• the stress is usually on the first syllable: BREMS
• final g in many standard pronunciations sounds closer to k at the end of a word or syllable, so Belag may sound like beh-LAHK

A rough breakdown:

• Brems = one syllable
• be
• lag

So: BREMS-be-lag, with the main stress at the front.

Not always.

Nicht neu literally means not new. That can imply:

• used
• not brand-new
• previously installed
• no longer new

But it does not always strongly mean old.

For example:

• something could be not new but still in good condition
• something could be used but fairly recent

So nicht neu is often a bit softer and more neutral than directly saying alt.

Compare:

• Der Bremsbelag ist nicht neu. = The brake pad is not new.
• Der Bremsbelag ist alt. = The brake pad is old.

The second one sounds more definite and stronger.