בדירה הזאת אין מזרן על המיטה, ולכן נצטרך לקנות מזרן חדש.

בדירה הזאת means in this apartment.

It is made of:

• ב־ = in
• דירה = apartment
• הזאת = this

So literally it is in apartment this, which is normal Hebrew structure.

If you said הדירה הזאת, that would mean this apartment as a noun phrase, without the idea of in. The sentence needs in this apartment, so Hebrew uses ב־ attached to the noun: בדירה הזאת.

In Hebrew, demonstratives like this usually come after the noun.

So:

• דירה הזאת / more standardly הדירה הזאת = this apartment
• המיטה הזאת = this bed
• המזרן הזה = this mattress

This is different from English, where this comes before the noun.

Also notice agreement:

• הזאת is feminine singular
• הזה is masculine singular

Since דירה is feminine, the sentence uses הזאת.

אין is the normal Hebrew word for there is no / there are no / does not have in this kind of sentence.

So:

• אין מזרן על המיטה = There is no mattress on the bed

Hebrew does not usually use לא for this structure.
לא is mainly used to negate verbs:

• לא קנינו מזרן = We didn’t buy a mattress
• לא נצטרך = We won’t need

But for existence, Hebrew uses יש / אין:

• יש מזרן = there is a mattress
• אין מזרן = there is no mattress

In present-tense Hebrew, sentences like there is / there are often do not use a separate verb like English is.

Instead, Hebrew commonly uses:

• יש = there is / there are
• אין = there is no / there are no

So:

• יש מזרן על המיטה = There is a mattress on the bed
• אין מזרן על המיטה = There is no mattress on the bed

This is just how Hebrew expresses existence.

על המיטה means on the bed.
במיטה means in bed or in the bed.

In this sentence, מזרן על המיטה makes sense because a mattress is physically on a bed frame.

Examples:

• הספר על המיטה = The book is on the bed
• הילד במיטה = The child is in bed

So על is the natural preposition here.

ולכן means and therefore / and so / therefore.

It is made of:

• ו־ = and
• לכן = therefore / so

Hebrew very often attaches ו־ directly to the next word.

So this part:

• ולכן נצטרך = and therefore we will need to

It connects the two parts of the sentence:

1. there is no mattress
2. therefore, we will need to buy one

נצטרך means we will need.

It is the future tense of the verb להצטרך / commonly discussed as the verb צריך in usage, from the idea of need.

Here:

• נ־ marks we
• the whole form נצטרך = we will need

So:

• נצטרך לקנות = we will need to buy

This is future because the buying has not happened yet.

After נצטרך (we will need), Hebrew uses the infinitive: לקנות (to buy).

So:

• נצטרך לקנות = we will need to buy

This is parallel to English need to buy.

לקנות is the infinitive form:

• ל־ = to
• קנות as part of the infinitive form of buy

Other examples:

• אני רוצה לקנות = I want to buy
• הם צריכים ללכת = They need to go

So the structure is very normal: finite verb + infinitive.

Yes, Hebrew could avoid repeating the noun in some contexts, but repeating מזרן is completely natural and clear.

The sentence says:

• אין מזרן... ולכן נצטרך לקנות מזרן חדש
• literally: There is no mattress... therefore we’ll need to buy a new mattress

This repetition is not awkward in Hebrew.

You could also hear:

• נצטרך לקנות אחד חדש = we’ll need to buy a new one

That is also natural, but the full noun מזרן חדש sounds a bit more explicit and straightforward.

Because מזרן is a masculine noun.

In Hebrew, adjectives must agree with the noun in gender and number.

So:

• מזרן חדש = a new mattress (masculine singular)
• מיטה חדשה = a new bed (feminine singular)

Since מזרן is masculine singular, the adjective is חדש.

Both exist, but they are different in style.

• הזאת is the more standard and widely taught form
• הזו is common in everyday spoken Hebrew

So you may hear:

• בדירה הזאת
• בדירה הזו

Both mean in this apartment.

For learners, הזאת is usually the safer standard form to recognize and use first.

Hebrew often puts the setting or location early in the sentence, especially when introducing what exists or does not exist somewhere.

So:

• בדירה הזאת אין מזרן על המיטה
• literally: In this apartment, there is no mattress on the bed

This is very natural Hebrew word order.

You could rearrange parts in some contexts, but the given order sounds normal and emphasizes the apartment as the setting.

You would replace אין with יש:

• בדירה הזאת יש מזרן על המיטה.
• In this apartment, there is a mattress on the bed.

And if that changes the conclusion, you might say:

• ולכן לא נצטרך לקנות מזרן חדש
• and therefore we won’t need to buy a new mattress

This is a useful pair to remember:

• יש = there is / there are
• אין = there is no / there are no