La persona antipática no ayuda.

In Spanish, singular countable nouns usually need an article or some other determiner.

So la persona can mean:

• the person in a specific context
• sometimes a general type of person, depending on context

You usually would not say just persona antipática no ayuda in normal Spanish. It sounds incomplete.

Here, la is doing the job that the does in English.

In Spanish, descriptive adjectives usually come after the noun.

So:

• la persona antipática = the unpleasant/unfriendly person

This is the most neutral, normal word order.

You can sometimes put adjectives before the noun in Spanish, but that often changes the tone, emphasis, or style. For a basic descriptive sentence, persona antipática is the standard order.

Because persona is a feminine noun.

Adjectives in Spanish usually agree with the noun they describe in:

• gender: masculine/feminine
• number: singular/plural

So:

• la persona antipática
• el hombre antipático
• las personas antipáticas

Even if the person is male, the noun persona is still grammatically feminine, so the adjective must also be feminine.

Yes. Persona is always grammatically feminine.

That means you say:

• la persona
• una persona
• la persona antipática

even if you are talking about a man.

This is an important difference between grammatical gender and biological sex. The grammar follows the noun persona, not necessarily the real-world gender of the person.

Antipático / antipática usually means something like:

• unpleasant
• unfriendly
• disagreeable
• not nice
• sometimes rude or annoying, depending on context

It does not mean apathetic.

English speakers sometimes connect it to antipathy, but in everyday Spanish it is commonly used to describe someone who is not likable or not warm.

So la persona antipática is more like:

• the unpleasant person
• the unfriendly person
• the rude person (in some contexts)

In Spanish, basic negation usually works by putting no directly before the verb.

So:

• ayuda = helps / is helping
• no ayuda = does not help / is not helping

This is the normal way to make a sentence negative in Spanish.

Ayuda is the third-person singular present tense of ayudar (to help).

So it can mean:

• he helps
• she helps
• it helps
• you help (formal usted)
• the person helps

In this sentence, it matches la persona, which is third-person singular:

• La persona antipática no ayuda.

It can mean either one, depending on context.

Spanish simple present often covers both:

• habitual action: helps
• current action: is helping

So no ayuda could mean:

• doesn’t help
• isn’t helping

The surrounding context tells you which meaning is intended.

Yes, depending on context.

Spanish present tense can describe:

• a specific situation: The unpleasant person isn’t helping.
• a general statement: An unpleasant person doesn’t help.

Also, la + singular noun can sometimes sound more generic in Spanish than the does in English.

But without more context, the most direct reading is usually:

• The unpleasant person doesn’t help / isn’t helping.

Yes. Ayudar often takes a direct object:

• Ayuda a su amiga. = She helps her friend.
• No ayuda a nadie. = He doesn’t help anyone.

Notice the personal a before a person:

• ayuda a la persona
• ayuda a su hermano

In your sentence, there is no object stated. It just says the person does not help.

Yes. That would simply mean:

• The person doesn’t help
• The person isn’t helping

Adding antipática gives extra description:

• La persona antipática no ayuda. = The unpleasant person doesn’t help.

So antipática is just modifying persona.

You could, but it is less neutral and less common in everyday speech.

Putting the adjective before the noun often adds a literary, emotional, or emphatic feel. It can sound more subjective or dramatic.

So:

• la persona antipática = normal, standard description
• la antipática persona = more marked, stylized, or emphatic

For a learner, la persona antipática is the safest and most natural choice.