Onako se predstavila.

Onako is an adverb. In this sentence it means something like that way, like that, or in that manner.

It usually points to a manner that is already known from context:

• someone has just described how she introduced herself
• or the speaker is reacting to the way she did it

Depending on tone, onako can sound:

• neutral: in that way
• slightly vague: sort of like that
• sometimes mildly judgmental or dismissive: like that

So the exact nuance depends a lot on context and intonation.

Se is the reflexive clitic.

The verb predstaviti means to introduce or to present someone/something.
But predstaviti se means to introduce oneself.

So:

• Predstavila je prijatelja. = She introduced a friend.
• Predstavila se. = She introduced herself.

English uses herself only if needed, but Croatian commonly uses se with this verb.

The ending -la shows that the subject is feminine singular in the past tense.

Croatian past tense agrees with the gender and number of the subject.

Compare:

• predstavio se = he introduced himself
• predstavila se = she introduced herself
• predstavilo se = it introduced itself
• predstavili su se = they introduced themselves, masculine or mixed group
• predstavile su se = they introduced themselves, all-feminine group

So this sentence tells you that the person was female.

It is the past tense, more specifically the Croatian perfect.

Croatian perfect is formed with:

• the present tense of biti = to be
• plus the l-participle

In full form, this would be:

• Ona se je predstavila.

But in normal modern Croatian, je is usually omitted with reflexive past forms like this, so you simply get:

• Ona se predstavila.

Since Croatian often drops subject pronouns, the sentence becomes:

• Onako se predstavila.

The infinitive is predstaviti se.

That is the dictionary form you would look up.

Related forms:

• predstaviti = to introduce, to present
• predstaviti se = to introduce oneself

So predstavila se is the feminine singular past form of predstaviti se.

Yes, predstaviti se is perfective.

That means it usually refers to a completed action:

• she introduced herself
• the introduction happened as a single whole event

The imperfective partner is:

• predstavljati se

Compare:

• Predstavila se. = She introduced herself.
  completed event
• Predstavljala se svima redom. = She was introducing herself to everyone one by one.
  ongoing, repeated, or habitual action

This is an important aspect pair in Croatian:

• predstaviti se = perfective
• predstavljati se = imperfective

Because Croatian often omits subject pronouns when they are clear from the verb form or the context.

In this sentence, predstavila already tells you:

• past tense
• feminine singular

So ona is not necessary.

You could say:

• Ona se onako predstavila.

But that would usually add emphasis, contrast, or clarity. In ordinary speech, leaving ona out is very natural.

Yes, Croatian word order is flexible.

Onako se predstavila is perfectly natural and puts some emphasis on onako:

• That’s how she introduced herself
• She introduced herself like that

Other possible orders include:

• Predstavila se onako.
• Ona se onako predstavila.
• Onako se ona predstavila.

The basic meaning stays similar, but the focus changes:

• sentence-initial onako emphasizes the manner
• sentence-initial predstavila se can sound more neutral or event-focused
• adding ona can create contrast, like she did it that way

Also, se is a clitic, so it usually appears near the beginning of the clause, often in the second position area.

Se is a clitic, which means it is a short unstressed word that cannot normally stand on its own and tends to appear in a fixed position near the beginning of the clause.

That is why:

• Onako se predstavila. sounds natural

But a form like:

• Onako predstavila se. is not the normal standard order.

Croatian clitics, including se, usually come after the first stressed element or in the clitic cluster position near the beginning of the sentence.

So in this sentence:

• Onako = first element
• se = clitic placed right after it
• predstavila = main verb form

No. Onako is a very flexible word in Croatian.

It can mean:

• like that
• that way
• so
• sometimes even something like kind of or more or less, depending on context

In Onako se predstavila, the most natural reading is about manner:

• she introduced herself that way

But in other contexts, onako can be vaguer or more conversational.

For example, Croatian learners often notice that onako is one of those common everyday words whose exact English equivalent changes with context.

Yes, it can.

With predstaviti se, Croatian can add the person or group to whom someone introduces herself, often in the dative.

For example:

• Predstavila se profesorici. = She introduced herself to the female professor.
• Predstavio se publici. = He introduced himself to the audience.

So the sentence you were given is just a shorter version without saying to whom she introduced herself.

The main change would be in the past participle.

Here are the matching forms:

• Onako se predstavio. = he introduced himself like that
• Onako se predstavila. = she introduced herself like that
• Onako se predstavilo. = it introduced itself like that
• Onako su se predstavili. = they introduced themselves like that, masculine or mixed group
• Onako su se predstavile. = they introduced themselves like that, all-feminine group

Notice that in the plural, you also need su:

• su se predstavili / predstavile

So Croatian past tense changes according to both gender and number.