היא באה לעבודה בלי מסכה, אבל בתיק יש לה מסכה חדשה.

Because היא means she, and the verb has to match a feminine singular subject.

• הוא בא = he comes / he came
• היא באה = she comes / she came

In this sentence, באה is the feminine singular form of the verb לבוא (to come).

A useful thing to know: in Hebrew, this form can often mean either came or comes, depending on context. In a sentence like this, it is usually understood as past: She came to work without a mask...

Hebrew works differently from English here. The form באה by itself is often the past tense form (came), but Hebrew also has present-tense forms that look similar in some verbs.

For learners, the important point is:

• in this sentence, היא באה לעבודה is naturally read as She came to work
• context usually tells you whether the meaning is past, habitual present, or something else

So you do not translate word-by-word mechanically; you use the context of the whole sentence.

The prefix ל־ usually means to.

So:

• עבודה = work
• לעבודה = to work

This is very common with places and destinations:

• לבית = to the house / home
• לבית הספר = to school
• לעיר = to the city
• לעבודה = to work

Because when ל־ attaches to a noun with ה־ (the), Hebrew usually combines them.

So:

• העבודה = the work / the job
• ל + העבודה becomes לעבודה

This is a standard contraction:

• ל + ה... often becomes לַ... in pronunciation and a combined written form

So לעבודה can mean to work or to the workplace/job, depending on context.

בלי means without.

Examples:

• בלי מים = without water
• בלי כסף = without money
• בלי מסכה = without a mask / without a mask on

It is a very common preposition.

Because the sentence is talking about not wearing any mask, not a specific one already known to the listener.

• בלי מסכה = without a mask
• בלי המסכה = without the mask

So the version in your sentence is more general and natural: she came without a mask.

This is a very important Hebrew pattern.

Hebrew often expresses possession with יש + an indirect object:

• יש לי = I have
• יש לך = you have
• יש לו = he has
• יש לה = she has

Literally, יש לה is something like there is to her, but in natural English it means she has.

So:

• יש לה מסכה חדשה = she has a new mask

Hebrew word order is flexible, and fronting בתיק puts special focus on the location.

• בתיק יש לה מסכה חדשה = In the bag, she has a new mask
• יש לה מסכה חדשה בתיק = She has a new mask in the bag

Both are possible, but the given sentence emphasizes where the mask is: in the bag.

This kind of fronting is very common in Hebrew.

Literally, בתיק means in the bag or sometimes just in a bag, depending on context.

Here, because the sentence is about her, it will usually be understood as in her bag, even though שלה is not stated.

If you want to say it explicitly, you could say:

• בתיק שלה = in her bag

Hebrew often leaves this kind of thing implicit when the context is clear.

It is made from:

• ב־ = in
• תיק = bag

So:

• תיק = bag
• בתיק = in a/the bag

Like ל־, the prefix ב־ often combines with ה־:

• ב + התיק becomes בתיק

So בתיק can mean in the bag.

In Hebrew, adjectives usually come after the noun.

So:

• מסכה חדשה = a new mask
• literally: mask new

This is normal Hebrew word order:

• בית גדול = a big house
• מכונית אדומה = a red car
• מסכה חדשה = a new mask

Because מסכה is a feminine noun, and adjectives must agree with the noun in gender and number.

So:

• מסכה = feminine singular
• therefore חדשה = feminine singular adjective

Compare:

• ספר חדש = a new book (masculine)
• מסכה חדשה = a new mask (feminine)

One clue is the ending ־ה, which often marks feminine nouns, though not always.

So:

• מסכה is feminine
• therefore verbs and adjectives connected to it should be feminine when relevant

That is why you get:

• מסכה חדשה

Not every noun ending in ־ה is feminine in every context, but it is a very common pattern and a useful clue.

אבל means but.

It connects the two parts of the sentence:

• היא באה לעבודה בלי מסכה = She came to work without a mask
• אבל בתיק יש לה מסכה חדשה = but in her bag she has a new mask

So the contrast is:

• she arrived without one on
• but she actually does have one with her

It is indefinite, so it means a new mask.

In Hebrew, definiteness usually appears with ה־ on the noun, and the adjective also agrees:

• מסכה חדשה = a new mask
• המסכה החדשה = the new mask

Since there is no ה־ here, the phrase is indefinite.

Yes, that would also be grammatical.

Compare:

• בתיק יש לה מסכה חדשה = stronger emphasis on in the bag
• יש לה בתיק מסכה חדשה = more neutral, closer to she has a new mask in her bag

Both are good Hebrew. The original just highlights the location first.