Она быстро пришла в сознание.

Пришла is the perfective past form of прийти, so it presents the action as a completed event: she came to / regained consciousness.

By contrast, приходила is imperfective and usually suggests a process, repetition, or a less clearly bounded event. In this sentence, Russian wants the idea of a definite result: she regained consciousness. That is why пришла is the natural choice.

In the past tense, Russian verbs agree with the subject in gender and number.

The subject is она (she), so the verb takes the feminine singular past ending:

• он пришёл = he came
• она пришла = she came
• оно пришло = it came
• они пришли = they came

So пришла tells you that the subject is feminine.

Yes, that is the literal structure, and it functions as a fixed expression meaning:

• to regain consciousness
• to come to
• to recover consciousness

So Она быстро пришла в сознание is an idiomatic Russian way to say that she regained consciousness quickly.

Because this expression uses в + accusative to show movement into a state.

Compare:

• в сознание = into consciousness / regaining consciousness
• в сознании = in consciousness / conscious

So:

• Она пришла в сознание = she regained consciousness
• Она уже была в сознании = she was already conscious

This is a common Russian pattern:
movement/change into a state often uses в + accusative.

It is in the accusative case.

The noun сознание is neuter, and for many neuter inanimate nouns, the nominative and accusative forms look the same:

• nominative: сознание
• accusative: сознание

So even though the form does not change visibly, it is still accusative because of the construction в сознание.

Быстро means quickly and modifies the whole event of regaining consciousness.

So the sentence means that the return to consciousness happened quickly. In natural English, depending on context, this could be:

• She quickly regained consciousness.
• She came to quickly.
• She regained consciousness soon afterward.

Yes. Russian word order is flexible, and the basic meaning stays the same:

• Она быстро пришла в сознание.
• Она пришла в сознание быстро.
• Быстро она пришла в сознание.

However, the different orders can slightly change the focus or emphasis.

The version you have, Она быстро пришла в сознание, is neutral and very natural.

Yes, if the subject is already clear from context.

You could say:

• Быстро пришла в сознание.

This is common in Russian when the subject is understood from the surrounding sentences. But if the sentence stands alone, она helps make it clear who regained consciousness.

It is generally neutral and very common.

Depending on style, Russian also has other ways to express a similar idea:

• прийти в сознание = neutral, standard
• очнуться = to come to, regain consciousness
• прийти в себя = literally come back to oneself, often broader: recover, pull oneself together, come around

So прийти в сознание is a standard and natural choice, especially when talking specifically about consciousness.

These mean different things:

• Она пришла в сознание = she regained consciousness
• Она была в сознании = she was conscious

So the first describes a change of state, while the second describes the state itself.

That is an important distinction in Russian:

• в сознание = into consciousness
• в сознании = in a conscious state

Not only. Сознание can also mean consciousness in a broader mental or philosophical sense.

For example, it can refer to:

• awareness
• consciousness
• mindset

But in the phrase прийти в сознание, it specifically means regaining consciousness after fainting, injury, etc.

So in this sentence, the meaning is the physical/medical one.

A few natural translations are:

• She quickly regained consciousness.
• She came to quickly.
• She quickly came to.

The closest in structure is She quickly came to, but She quickly regained consciousness is often the clearest translation for learners.