Я спросила таксиста, где лучше выйти, чтобы перейти улицу по зебре.

Спросила is the past tense feminine singular form of спросить.

In Russian past tense, the verb agrees with the subject in gender and number:

• я спросил = I asked (male speaker)
• я спросила = I asked (female speaker)
• мы спросили = we asked

So this sentence tells you that the speaker is female.

Because таксиста is accusative singular, and таксист is an animate masculine noun.

With animate masculine nouns, the accusative looks like the genitive:

• nominative: таксист
• genitive: таксиста
• accusative: таксиста

The verb спросить can take the person asked as a direct object:

• спросить таксиста = to ask the taxi driver

So таксиста is there because he is the person being asked.

Both patterns exist, but they are not exactly the same structure.

Russian commonly allows:

• спросить кого = ask someone
• спросить у кого = ask someone / ask from someone

So these are both possible:

• Я спросила таксиста, где лучше выйти.
• Я спросила у таксиста, где лучше выйти.

The version in your sentence uses спросить кого + the content of the question. That is a very normal pattern, especially when the focus is on asking a person something.

Here где means at what place / where along the route it is best to get out.

Even though выйти is a motion verb, this question is really about the location of the stop, not the destination after getting out. In English we also say Where is it better to get out?

So:

• где лучше выйти = where it is better to get out
• куда выйти would sound more like to what place should one go out, which is not the idea here

A more explicit version would be:

• На какой остановке лучше выйти? = At which stop is it better to get out?

Лучше is the comparative form of хорошо and here it works in an impersonal expression:

• лучше выйти = it is better to get out

Russian often leaves out the person for whom something is better when it is obvious from context. In English we might say:

• Where is it better for me to get out?

In Russian, мне is often omitted if it is clear:

• где лучше выйти
  rather than
• где мне лучше выйти

Both are possible, but the shorter version is very natural.

Because both actions are seen as single completed actions:

• выйти = to get out, to exit once and complete that action
• перейти = to cross and complete the crossing

That fits the context: the speaker wants to know the best place to get out so that they can then cross the street.

If you used the imperfective forms, the focus would shift more toward process, repetition, or general activity:

• выходить
• переходить

But here the meaning is specific and one-time, so perfective is the natural choice.

Чтобы introduces a purpose clause:

• чтобы перейти улицу по зебре = in order to cross the street at the crosswalk

This is one of the most common ways to say so that / in order to in Russian.

When the subject is the same as in the main clause, Russian often uses чтобы + infinitive:

• Я пришёл, чтобы помочь. = I came to help.
• Она остановилась, чтобы посмотреть. = She stopped to look.

So in your sentence, the speaker asked where to get out in order to cross the street properly.

Yes, that is possible, but it sounds more explicit.

Compare:

• чтобы перейти улицу = in order to cross the street
• чтобы я перешла улицу = so that I could cross the street / so that I would cross the street

When the subject is the same and obvious, Russian usually prefers the shorter infinitive construction:

• чтобы перейти

If the subject needs to be stated clearly, or if it is different from the main clause, then a finite verb is common:

• Я объяснил ему, где остановиться, чтобы он перешёл улицу по зебре.

Because перейти directly takes the thing being crossed as its object.

So Russian says:

• перейти улицу = cross the street
• перейти дорогу = cross the road

The verb itself already contains the idea of going across from one side to the other, so no extra preposition is needed.

That is why you get:

• улица → улицу in the accusative singular

Yes, зебра literally means zebra, but in everyday Russian it also means a zebra crossing / crosswalk, because of the striped markings.

So:

• по зебре = on the zebra crossing / using the crosswalk

This is a very common colloquial expression.

The more formal term is:

• пешеходный переход = pedestrian crossing

So you could also say:

• чтобы перейти улицу по пешеходному переходу

But по зебре is shorter and very natural in everyday speech.

Because the idea is crossing by means of / along the marked crossing, not crossing the zebra itself as an object.

The preposition по often expresses movement along a surface, line, route, or marked path:

• идти по дороге = walk along the road
• ехать по мосту = drive over the bridge
• перейти по мосту = cross by way of the bridge

So по зебре means using the zebra crossing as the path.

Russian uses commas to separate subordinate clauses very regularly.

In this sentence:

• Я спросила таксиста, где лучше выйти, чтобы перейти улицу по зебре.

the first comma comes before the indirect question:

• где лучше выйти

The second comma comes before the purpose clause introduced by чтобы:

• чтобы перейти улицу по зебре

So the structure is:

• main clause: Я спросила таксиста
• subordinate clause 1: где лучше выйти
• subordinate clause 2: чтобы перейти улицу по зебре

Yes. Russian word order is flexible, and changes often affect emphasis more than basic meaning.

Your version is neutral and natural:

• Я спросила таксиста, где лучше выйти, чтобы перейти улицу по зебре.

Other possible versions include:

• Я спросила у таксиста, где лучше выйти, чтобы перейти улицу по зебре.
• Где лучше выйти, чтобы перейти улицу по зебре, я спросила таксиста.

The original order sounds like a straightforward statement in normal conversation or narration.