Ayudaron a la víctima.

Ayudaron is the preterite (simple past) form of ayudar and it is third person plural.

So it matches:

• they helped
• or, depending on context, you all helped (ustedes)

In this sentence, with no other context, an English speaker will usually read it as they helped.

Spanish often drops subject pronouns because the verb ending already shows who the subject is.

• Ayudaron already tells you it is third person plural
• So ellos ayudaron is possible, but usually unnecessary

You would add ellos only for emphasis, contrast, or clarity:

• Ellos ayudaron a la víctima, no los demás.
  They helped the victim, not the others.

Yes. Grammatically, ayudaron can also mean you helped when the subject is ustedes.

In Spain:

• vosotros ayudasteis = you all helped (informal)
• ustedes ayudaron = you all helped (formal)

So in Spain, if you see ayudaron without context, they helped is usually the most natural reading.

This is the personal a.

In Spanish, when the direct object is a specific person (or sometimes a personified being), you usually put a before it.

So:

• Ayudaron a la víctima.
• not Ayudaron la víctima.

Even though English does not use this a, Spanish normally does here because the victim is a person.

Because al is only the contraction of a + el.

• a + el = al
• a + la = a la (no contraction)

Since víctima is a feminine noun, it takes la:

• a la víctima

Spanish usually uses the definite article more often than English does with specific nouns.

Here, la víctima means the victim, referring to a specific victim already known from the situation or context.

So:

• Ayudaron a la víctima = They helped the victim

Leaving out the article here would sound unnatural in standard Spanish.

Yes. Víctima is a grammatically feminine noun, no matter whether the person is male or female.

So you still say:

• la víctima

Even if the victim is a man, the noun itself stays feminine:

• La víctima era un hombre.
  The victim was a man.

This is grammatical gender, not necessarily biological sex.

Because the preterite usually presents the action as a completed event.

• Ayudaron a la víctima. = They helped the victim.
  This sounds like a finished action.

By contrast:

• Ayudaban a la víctima. = They were helping the victim / They used to help the victim.

So the choice tells you how the speaker views the action:

• preterite = completed whole event
• imperfect = ongoing, repeated, background, or habitual

In standard Spanish, you would normally use a direct object pronoun:

• La ayudaron. = They helped her / They helped the victim.

This is because ayudar is usually treated as taking a direct object.

You still see a with the full noun:

• Ayudaron a la víctima

But with the pronoun:

• La ayudaron

In parts of Spain, learners may also hear some variation with object pronouns in real speech, but la ayudaron is the safest standard form for this sentence.

It is pronounced roughly as ah-yoo-DAH-ron.

It has no written accent because it follows the normal Spanish stress rules:

• words ending in n, s, or a vowel are usually stressed on the second-to-last syllable

So ayu-da-ron is naturally stressed on da, and no accent mark is needed.