La médica ayudó al soldado.

Médica is the feminine form of médico, meaning doctor or physician. So la médica means the female doctor.

In Spain, feminine job titles are very common when talking about a woman:

• el médico = the male doctor
• la médica = the female doctor

You may also hear doctora, but médica clearly means a woman who is a medical doctor.

Because the stress falls on the third-to-last syllable: MÉ-di-ca.

In Spanish, words stressed on the third-to-last syllable always take a written accent. That is why médica must be spelled with é.

Ayudó is the preterite tense, third-person singular, from ayudar.

So it means:

• he helped
• she helped
• it helped

In this sentence, it means she helped, because the subject is la médica.

Ayudó and ayudaba are both past tenses, but they are used differently.

• ayudó = preterite → a completed action
• ayudaba = imperfect → an ongoing, repeated, or background action

So:

• La médica ayudó al soldado = the doctor helped the soldier
  → one completed action

• La médica ayudaba al soldado = the doctor was helping / used to help the soldier
  → ongoing or repeated in the past

The accent mark shows that the stress is on the last syllable: a-yu-DÓ.

It also helps distinguish it from ayudo, which means I help in the present tense.

So:

• ayudo = I help
• ayudó = he/she helped

That small accent changes both pronunciation and meaning.

This is because of the personal a.

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

Here, the soldier is a specific person receiving the action of helping, so Spanish says:

La médica ayudó al soldado.

Without that a, the sentence would sound incorrect in standard Spanish.

Because a + el always contracts to al.

So:

• a + el soldado → al soldado

This is a standard contraction in Spanish.
Another common one is:

• de + el → del

Spanish often leaves out subject pronouns because the verb form and context usually make the subject clear.

In this sentence, the subject is already stated as la médica, so there is no need to add ella.

Spanish prefers:

• La médica ayudó al soldado.

Not usually:

• Ella la médica ayudó al soldado.

If you removed the noun, then Ayudó al soldado could mean He helped the soldier or She helped the soldier, depending on context.

The most neutral and natural order here is:

La médica ayudó al soldado.
subject + verb + object

Spanish word order is more flexible than English, so other orders are possible, but they usually sound more marked or emphatic.

For example:

• La médica ayudó al soldado. = neutral
• Ayudó al soldado la médica. = possible, but more stylistic or emphatic

So for everyday use, the original order is the best one to learn first.