هي تزيل البقعة من القميص.

It can be left out.

Arabic verbs already show person, number, and gender, so تزيل by itself already tells you the subject is third-person feminine singular. That means:

تزيل البقعة من القميص
can already mean
She removes the stain from the shirt.

Adding هي makes the subject explicit. That can be useful for:

• emphasis
• contrast, as in she removes it, not someone else
• clarity in context

So both are possible, but هي is not strictly necessary.

In the imperfect tense, Arabic adds prefixes to show who is doing the action.

Here, تـ marks third-person feminine singular, so تزيل means she removes / she is removing.

A very common learner point: the same تـ can also be used for you masculine singular in other contexts. So:

• هي تزيل = she removes
• أنتَ تزيل = you remove to one male

The context or the explicit pronoun tells you which one is meant.

The dictionary form is usually the past tense verb أزالَ, meaning to remove.

Its present/imperfect form is يُزيلُ = he removes.
When the subject is هي, it becomes تُزيلُ = she removes.

So the pattern is:

• أزالَ = he removed
• يُزيلُ = he removes
• تُزيلُ = she removes

It can mean either one, depending on context.

The Arabic imperfect tense is broader than the English simple present. تزيل can express:

• a present action: she is removing
• a habitual action: she removes
• sometimes even a near future sense, depending on context

So Arabic does not force the same exact distinction that English makes between removes and is removing.

Because الـ is the definite article, like the in English.

So:

• البقعة = the stain
• القميص = the shirt

Without الـ, they would usually be indefinite:

• بقعة = a stain
• قميص = a shirt

In this sentence, both nouns are specific and definite.

من means from.

It shows the point of removal or separation:

• the stain is being removed from the shirt

This is a very common use of من in Arabic: it marks where something comes from or what something is separated from.

This sentence uses an explicit subject pronoun first:

هي تزيل البقعة من القميص

So the order is basically:

• هي = subject
• تزيل = verb
• البقعة = object
• من القميص = prepositional phrase

That is close to SVO in English terms.

Arabic also allows verb-first order very naturally, so you could also have:

تزيل البقعة من القميص

That is also correct. Using هي at the front makes the subject more explicit.

البقعة is the direct object because it is the thing being removed.

In fully vowelled MSA, the sentence would be:

هِيَ تُزيلُ البُقْعَةَ مِنَ القَميصِ

The endings show the grammar:

• تُزيلُ ends in ـُ because it is an imperfect verb in the normal indicative form
• البُقْعَةَ ends in ـَ because it is the direct object, so it is accusative
• القَميصِ ends in ـِ because it comes after the preposition من, so it is genitive

In normal Arabic writing, these short vowels are usually not written, so learners often have to infer them from grammar.

Because ب and ق are moon letters.

With moon letters, the l of ال is pronounced normally:

• البقعة = al-buqʿa
• القميص = al-qamīṣ

If the noun began with a sun letter, the l sound would assimilate instead. For example:

• الشمس is pronounced ash-shams, not al-shams

So in this sentence, you pronounce ال fully both times.

Yes.

In Arabic, هي is the pronoun for feminine singular. That can refer to:

• a female person = she
• a grammatically feminine thing = it

So outside this sentence, هي does not always mean a human female. It can also refer back to a feminine noun such as السيارة or البقعة.

In this sentence, though, if the meaning given is she removes the stain from the shirt, then هي is being understood as she.