אני שומע עליה הרבה, אבל אני לא מכיר אותה.

Because שומע is the masculine singular present-tense form.

Hebrew present tense agrees with the subject in gender and number. So:

• אני שומע = I hear / I am hearing said by a male
• אני שומעת = the same thing said by a female

The same applies later in the sentence:

• אני לא מכיר = said by a male
• אני לא מכירה = said by a female

So if a woman were saying the whole sentence, it would be:

אני שומעת עליה הרבה, אבל אני לא מכירה אותה.

Because they do two different grammatical jobs.

• עליה means about her or on her
• אותה means her as a direct object

In this sentence:

• אני שומע עליה הרבה = I hear a lot about her
• אני לא מכיר אותה = I don’t know her

So English uses her in both places, but Hebrew changes the form depending on whether it comes after a preposition or is a direct object.

עליה is the preposition על plus a pronoun ending.

Here:

• על = on / about
• עליה = on her / about her

This is part of a common Hebrew pattern where prepositions attach directly to pronouns:

• עלי = on/about me
• עליך = on/about you
• עליו = on/about him
• עליה = on/about her

In this sentence, the natural translation is about her, not literally on her.

Yes, שומע basically means hear, but the preposition after it changes the meaning.

• לשמוע משהו = to hear something
• לשמוע על מישהו/משהו = to hear about someone/something

So:

• אני שומע אותה would mean I hear her
• אני שומע עליה means I hear about her

That is why עליה is necessary here.

Here הרבה means a lot.

So:

• אני שומע עליה הרבה = I hear a lot about her

It is very common in Hebrew to use הרבה this way after a verb:

• אני עובד הרבה = I work a lot
• הוא מדבר הרבה = He talks a lot
• אנחנו נוסעים הרבה = We travel a lot

Depending on context, הרבה can also mean many/much, but here it is an adverb: a lot.

Because Hebrew has more than one way to say know, and they are used differently.

• יודע = know a fact, know information, know how
• מכיר = know a person, be familiar with, be acquainted with

So:

• אני יודע את התשובה = I know the answer
• אני מכיר אותה = I know her

In this sentence, the speaker means I’m not acquainted with her / I don’t know her personally, so מכיר is the correct choice.

Sometimes, yes. להכיר can mean to know / be familiar with / recognize, depending on context.

But in this sentence, because the contrast is:

• I hear a lot about her
• but I don’t know her

the meaning is clearly know her personally / be acquainted with her, not recognize her.

Because Hebrew usually does not use a present-tense form of to be in ordinary sentences.

So:

• אני שומע literally looks like I hearing
• but it means I hear or I am hearing

Likewise:

• אני לא מכיר אותה = I do not know her

This is normal Hebrew grammar. In the present tense, Hebrew generally just uses the participle-style form like שומע, מכיר, עובד, גר, and so on.

It can mean either one, depending on context.

Hebrew present tense often covers both:

• simple present: I hear about her a lot
• present progressive: I am hearing about her a lot

In most cases, English speakers translate it as I hear a lot about her, because that sounds more natural in English here.

Because לא is the standard Hebrew word for not, and it usually comes right before the thing being negated.

So:

• אני לא מכיר אותה = I do not know her

This is the normal word order in Hebrew.

You can think of it as:

• אני = I
• לא = not
• מכיר = know/am acquainted with
• אותה = her

Yes, often it would.

You could say:

אני שומע עליה הרבה, אבל לא מכיר אותה.

That is natural Hebrew too. Repeating אני makes the sentence a little clearer or slightly more explicit, but both versions are fine.

So:

• אני שומע עליה הרבה, אבל אני לא מכיר אותה = fully explicit
• אני שומע עליה הרבה, אבל לא מכיר אותה = also natural

אבל means but.

It connects the two contrasting ideas:

• I hear a lot about her
• but
• I don’t know her

So the speaker is showing a contrast between having heard about someone and actually knowing that person.

Only the pronouns referring to her would change to him.

So:

• עליה would become עליו = about him
• אותה would become אותו = him

The sentence would be:

אני שומע עליו הרבה, אבל אני לא מכיר אותו.

If the speaker were also female, then the verbs would change too:

אני שומעת עליו הרבה, אבל אני לא מכירה אותו.

They both relate to she/her, but they are used differently.

• היא = she (subject form)
• אותה = her (direct object form)

Examples:

• היא מדברת = She is speaking
• אני מכיר אותה = I know her

So in this sentence, אותה is used because her is the object of know.

The given order is the most natural and neutral one.

• אני שומע עליה הרבה

Hebrew does allow some flexibility, but changing the order can sound more marked or stylistically different. For a learner, the safest pattern is:

subject + verb + complement + הרבה

So it is best to learn this sentence exactly as written.