El piñón está sucio.

Spanish usually uses estar for a temporary state or condition, and ser for identity, essence, or what something is.

So El piñón está sucio uses está because dirty is being treated as a condition the thing is in right now.

• está sucio = it is dirty
• es sucio = it is dirty by nature / it is a dirty thing or a dirty person habitually

With objects, estar sucio is the normal choice when you mean that something needs cleaning.

The accent mark shows which syllable is stressed: es-TÁ.

It also helps distinguish this form from esta, which without an accent usually means this in modern Spanish usage:

• está = is
• esta = this

So the accent is important both for pronunciation and for meaning.

The written accent shows that the stress falls on the last syllable: pi-ÑÓN.

Without the accent, Spanish spelling rules would make you stress it differently. The accent tells you the correct pronunciation.

So:

• piñón → stress on the final syllable

The letter ñ is a separate letter in Spanish. It sounds like the ny in canyon or onion, although the exact Spanish sound is a bit cleaner and more focused.

So piñón is roughly like pee-NYON.

It is not the same as a plain n.
Compare:

• n = normal n sound
• ñ = ny sound

Because piñón is a masculine noun, so it takes the masculine singular article el.

In Spanish, nouns have grammatical gender, and the article has to match:

• el for masculine singular
• la for feminine singular

So:

• el piñón
• not la piñón

Usually, you learn the noun together with its article: el piñón.

While many masculine nouns end in -o, not all do. Endings like -ón are often masculine, but the safest habit is to memorise the article with the noun.

So instead of learning just piñón, learn:

• el piñón

That way you automatically know its gender.

Adjectives in Spanish must agree with the noun they describe in gender and number.

Since piñón is masculine singular, the adjective must also be masculine singular:

• el piñón está sucio

If the noun were feminine singular, you would use sucia:

• la mesa está sucia

If it were plural, you would use sucios or sucias:

• los piñones están sucios
• las mesas están sucias

In Spanish, descriptive adjectives often come after the noun.

So Spanish says:

• el piñón sucio
  literally: the pinion/pine nut dirty

That is the normal word order for many everyday descriptions. In your sentence, the adjective comes after estar:

• El piñón está sucio

This is completely standard.

Yes. In Spanish, piñón can have different meanings depending on context. Common ones include:

• a pine nut
• a pinion/gear sprocket in mechanical contexts

So if you saw this sentence by itself, the exact noun meaning would come from the context. Grammatically, though, the sentence works the same way either way.

Normally, no. In a standard sentence like this, you would usually keep the article:

• El piñón está sucio.

Spanish uses articles more often than English does. Leaving out el here would sound incomplete or unnatural in most ordinary contexts.

You need to make the article, noun, verb, and adjective all agree in the plural:

• Los piñones están sucios.

Changes:

• el → los
• piñón → piñones
• está → están
• sucio → sucios

This is a good example of how agreement works across the whole sentence in Spanish.

A simple guide is:

el pee-NYON es-TA SOO-syo

A bit more naturally in Spanish:

• el = short, light ehl
• piñón = pee-NYON
• está = es-TA
• sucio = SOO-syo

The strongest stresses are on:

• -ñón
• -tá
• su-

So the rhythm is roughly:

el pi-ÑÓN es-TÁ SU-cio