אתמול הוא היה בבית כל היום.

Yesterday he was at home all day.

Breakdown of אתמול הוא היה בבית כל היום.

• הוא: he
• בית: home
• ב: at
• יום: day
• אתמול: yesterday
• להיות: to be
• כל: all

Questions & Answers about אתמול הוא היה בבית כל היום.

Is אתמול connected to the direct object marker את?

No. אתמול is a single word that means yesterday.

It only happens to begin with the letters את, but it is not the same word as the direct object marker את.

So here:

• אתמול = yesterday
• not את
  • something else

What does each word in the sentence do?

Word by word:

• אתמול = yesterday
• הוא = he
• היה = was
• בבית = at home / in the house
• כל היום = all day / the whole day

So the structure is basically:

• Yesterday
  • he
    • was
      • at home
        • all day

Why is היה used here if Hebrew often leaves out to be?

Hebrew usually leaves out to be only in the present tense.

So:

• הוא בבית = he is at home
• but
• הוא היה בבית = he was at home

In other words:

• present: no separate word for is
• past: you must use a past form of to be, here היה

That is why this sentence needs היה.

What form is היה, exactly?

היה is the past tense, masculine singular form of the verb להיות (to be).

Here it matches הוא (he).

A few useful comparisons:

• הוא היה = he was
• היא הייתה = she was
• אני הייתי = I was
• הם היו = they were (masculine or mixed group)
• הן היו = they were (feminine)

So the sentence is specifically about a male singular person.

If היה already means he was, why is הוא also there?

Good question. Hebrew past-tense verbs already show person, number, and often gender, so היה by itself can already suggest he was.

But in modern Hebrew, using the subject pronoun is very common and natural.

So:

• היה בבית כל היום can be understood from context
• הוא היה בבית כל היום is clearer and more neutral in everyday speech

So הוא is not strictly necessary in every context, but it is very normal.

What exactly does בבית mean, and why is it written as one word?

בבית contains the preposition ב־, which means in / at, attached directly to the next word.

So Hebrew often writes this kind of preposition as part of the word:

• ב
  • בית / הבית → בבית

That is why there is no separate word for at.

In this sentence, בבית most naturally means at home.

Depending on context, it can also mean in the house, but with this sentence the usual English translation is at home.

Why does כל היום mean all day, and how is that different from כל יום?

כל means all / every, but the meaning changes depending on what follows.

• כל היום = all day / the whole day
• כל יום = every day

So the ה in היום matters.

Here, כל היום refers to the entire duration of that one day:

• אתמול הוא היה בבית כל היום = Yesterday he was at home all day

But:

• הוא בבית כל יום = He is at home every day

Is the word order fixed, or could the sentence be arranged differently?

The word order is somewhat flexible.

אתמול הוא היה בבית כל היום is very natural because אתמול is placed first to set the time frame right away: as for yesterday...

You could also hear other orders, such as:

• הוא היה בבית כל היום אתמול

That still means roughly the same thing.

But not every possible order sounds equally natural. The version you were given is a very common, smooth way to say it.

A helpful idea:

• putting אתמול first emphasizes yesterday
• putting בבית earlier keeps the main statement easy to follow
• כל היום usually stays together as one time expression

How would this sentence change in the present tense?

In the present tense, Hebrew normally drops to be.

So:

• אתמול הוא היה בבית כל היום = Yesterday he was at home all day
• היום הוא בבית כל היום = Today he is at home all day
• הוא בבית כל היום = He is at home all day

Notice that היה disappears in the present.

How is the whole sentence pronounced?

A simple transliteration is:

etmol hu haya babayit kol hayom

A rough syllable-by-syllable guide:

• et-mol
• hu
• ha-ya
• ba-ba-yit
• kol
• ha-yom

So the full sentence is:

etmol hu haya babayit kol hayom