לפני שאת מדברת, תצביעי.

לפני means before.

In this sentence, it introduces a whole clause:

לפני שאת מדברת = before you speak

A very common Hebrew pattern is:

לפני ש־... = before ...

It is really ש + את.

• ש־ is a connecting word, often like that / when
• את here means you in the feminine singular

So שאת מדברת means something like that you speak / when you speak.

Also, this את is not the direct object marker. Here it is the pronoun you.

Because all the relevant forms are feminine singular:

• את = you to one female
• מדברת = feminine singular form of speaking
• תצביעי = feminine singular you will / you should point, vote, raise your hand

If you were speaking to one male, you would say:

לפני שאתה מדבר, תצביע.

This is a very common thing in Hebrew.

Even though מדברת is formally a present-tense form, Hebrew often uses the present after words like לפני ש־ in places where English uses before you speak.

So the Hebrew is natural even though, word-for-word, it may look closer to before you are speaking.

This is especially common in everyday spoken Hebrew.

Yes.

לפני שתדברי, תצביעי. is also correct and natural.

The difference is roughly this:

• לפני שאת מדברת = very natural, common in everyday speech
• לפני שתדברי = also natural, a bit more explicitly future in feel

A learner should understand both.

In modern spoken Hebrew, people very often use the future form as a command.

So:

• תצביעי = normal everyday way to tell one female raise your hand / point
• הצביעי = true imperative, but it sounds more formal, more written, or more forceful

This happens with many verbs in Hebrew, not just this one.

It comes from the verb להצביע.

That verb can mean different things depending on context, such as:

• to point
• to vote
• to indicate
• to raise your hand

In this sentence, because it says before you speak, the intended meaning is most likely raise your hand.

So the context determines which meaning of להצביע is meant.

Because in Hebrew, להצביע by itself can already imply raising your hand to signal that you want to speak, especially in a classroom or meeting context.

So Hebrew often leaves hand unstated when it is obvious from the situation.

If someone wanted to be more explicit, they might say something like:

תרימי את היד לפני שאת מדברת
which literally says raise your hand before you speak

But תצביעי is very natural in the right context.

To one male:

לפני שאתה מדבר, תצביע.

To several people:

לפני שאתם מדברים, תצביעו.

In everyday Hebrew, the plural masculine form is commonly used for mixed groups as well.

A rough pronunciation is:

lifnei she'at medaberet, tatsbi'i

A couple of useful notes:

• שאת sounds like she-at
• תצביעי has the sequence bi-i, so you hear a slight separation there: tats-bi-i

You do not need a perfect transliteration to understand it, but that is a good rough guide.