Az aktiválás gyors.

Hungarian has two forms of the definite article: a and az.
You use az before a vowel sound and a before a consonant sound.

Since aktiválás starts with the vowel a, the correct form is az aktiválás.

This is similar to English a/an:

• a book
• an apple

So:

• a ház = the house
• az aktiválás = the activation

In Hungarian, the verb to be is often omitted in the present tense, in the 3rd person.

So Az aktiválás gyors. literally looks like:

• Az aktiválás = the activation
• gyors = fast

But the full meaning is The activation is fast.

This happens very often in Hungarian:

• A ház nagy. = The house is big.
• Az étel finom. = The food is tasty.

But the verb appears in other persons:

• Gyors vagyok. = I am fast.
• Gyors vagy. = You are fast.

And it also appears in past or future:

• Az aktiválás gyors volt. = The activation was fast.

Because gyors is a predicate adjective here. It is describing the subject in a full sentence: The activation is fast.

In Hungarian, when an adjective is part of the predicate, it usually comes after the noun:

• Az autó gyors. = The car is fast.
• A feladat nehéz. = The task is difficult.

But when the adjective comes directly before the noun, it works like English fast activation:

• a gyors aktiválás = the fast activation

So the difference is:

• Az aktiválás gyors. = The activation is fast.
• A gyors aktiválás = the fast activation

Aktiválás is a noun. It means activation.

It is built from the verb aktivál = to activate, plus the noun-forming suffix -ás.

So:

• aktivál = activate
• aktiválás = activation / the act of activating

This -ás / -és ending is very common in Hungarian for making action nouns:

• tanít = teach → tanítás = teaching
• indít = start, launch → indítás = starting, launch
• fizet = pay → fizetés = payment, salary

Not in this sentence.

Hungarian does not have grammatical gender, so there is no masculine/feminine agreement to worry about.
Also, with a singular subject like az aktiválás, the adjective stays in its basic form:

• Az aktiválás gyors.

If the subject is plural, the predicate adjective is usually plural too:

• Az aktiválások gyorsak. = The activations are fast.

So in your sentence, gyors is simply the normal singular form.

Yes, you could.

Hungarian word order is flexible, and changing the order often changes the emphasis rather than the basic meaning.

• Az aktiválás gyors. = neutral statement
• Gyors az aktiválás. = emphasis on fast

The second version might sound like:

• The activation is fast
• or even The activation is fast, not slow

So both are possible, but Az aktiválás gyors. is the more neutral basic form.

A few useful points:

• gy is a special Hungarian sound. It is softer than a normal English g. It is roughly like a blended dy sound.
• o is short here.
• r is rolled or tapped.
• s in Hungarian is pronounced like English sh.
• sz would be the ordinary English s, but that letter combination does not appear here.

So gyors sounds roughly like dyorsh.

Also, Hungarian stress normally falls on the first syllable:

• GYORS
• AK-ti-vá-lás

Usually not in a normal sentence.

Hungarian normally wants an article here:

• Az aktiválás gyors.

If you remove the article, it can sound unnatural, incomplete, or like a heading, note, or technical label rather than an ordinary sentence.

So for standard everyday Hungarian, keep the article:

• Az aktiválás gyors.

It can do both, depending on context.

In Hungarian, the definite article is often used more broadly than in English. So az aktiválás can refer to:

• a specific activation already known from context, or
• activation as a general process or concept

So the exact English translation depends on the situation. But grammatically, az aktiválás is a normal and natural Hungarian subject phrase.