La revisión de seguridad está aquí.

Because revisión is a singular feminine noun, so it takes the feminine singular definite article la.

• la revisión
• not el revisión

Spanish articles have to agree with the noun in gender and number.

In Spanish, every noun has a grammatical gender. Revisión is feminine, which is common for nouns ending in -ión:

• la revisión
• la canción
• la decisión
• la información

This is grammatical gender, so it does not imply anything about real-world gender.

De seguridad is a prepositional phrase modifying revisión. It tells you what kind of review/inspection it is.

This structure is very common in Spanish:

• revisión de seguridad
• control de calidad
• tarjeta de crédito

English often uses a noun directly before another noun, like security review, but Spanish usually connects them with de.

Because estar is normally used for location.

Here, the sentence is saying that something is here / is present here, so Spanish uses estar:

• La revisión de seguridad está aquí.

Compare:

• es = identity, definition, what something is
• está = location, condition, temporary state

So if you are talking about where something is, estar is the usual choice.

The accent mark in está shows the correct stress: es-TÁ.

It also helps distinguish forms in writing. In this case, está is the third-person singular form of estar:

• yo estoy
• tú estás
• él/ella/usted está

Accent marks in Spanish are not optional; they are part of the correct spelling.

Yes. That is completely natural.

Both are correct:

• La revisión de seguridad está aquí.
• Aquí está la revisión de seguridad.

The difference is mostly focus:

• La revisión de seguridad está aquí puts the topic first.
• Aquí está la revisión de seguridad emphasizes here it is or draws attention to its arrival/presence.

Often, yes. In much of Latin America, aquí and acá can both mean here, but there can be small regional and stylistic differences.

Very roughly:

• aquí often sounds a bit more exact or specific
• acá can sound a bit more conversational or directional in some regions

So La revisión de seguridad está aquí and La revisión de seguridad está acá may both be understood, but aquí is the safer all-purpose choice for learners.

It is grammatical and understandable, but the most natural wording depends on the situation.

For example:

• At an airport or checkpoint, people may more naturally say el control de seguridad
• For a formal review, audit, or inspection, revisión de seguridad can fit well
• In technical or workplace contexts, you might also hear inspección de seguridad or chequeo de seguridad, depending on the country

So the sentence is fine, but Spanish often has multiple context-specific ways to express this idea.

Because revisión segura would mean something more like a safe review, not a security review.

Spanish often uses:

• noun + de + noun

to express the type or purpose of something.

So:

• revisión de seguridad = a review related to security
• revisión segura = a review that is safe

That is an important difference.

It is pronounced roughly reh-bee-SYON in much of Latin America.

A few helpful points:

• r in revisión is a light Spanish r
• v in Spanish sounds closer to a soft b sound
• the stress falls on the last syllable: revi-SIÓN

And in está aquí, the stress is:

• es-TÁ
• a-QUÍ

Both words carry written accent marks because the stress is important.

Usually not in this sentence.

Spanish generally uses the article with specific nouns more often than English does. Since this is talking about a specific review/inspection, la sounds normal and expected:

• La revisión de seguridad está aquí.

Without la, the sentence would sound incomplete or unnatural in standard usage.