מאחורי הבית יש חצר, ומעל המטבח יש גג ישן.

יש is the Hebrew existential word meaning there is / there are. In present-tense Hebrew, you usually do not use a present-tense form of to be the way English does. So to say that something exists in a place, Hebrew says:

• יש חצר = there is a courtyard
• יש גג ישן = there is an old roof

If you want the negative, Hebrew uses אין:

• מאחורי הבית אין חצר = There is no courtyard behind the house

Both word orders can work, but putting the location first is very natural in Hebrew, especially when describing a place or setting the scene.

• מאחורי הבית יש חצר = Behind the house, there is a courtyard
• יש חצר מאחורי הבית = There is a courtyard behind the house

The sentence you have sounds like a description of what is where.

מאחורי means behind, used before a noun:

• מאחורי הבית = behind the house

It is a preposition of location, just like מעל in the second half of the sentence. English speakers often expect a separate word structure, but in Hebrew this is a normal single preposition followed by a noun phrase.

A helpful basic distinction is:

• מאחורי + noun = behind something
• מאחור = in back / behind, more on its own

Examples:

• מאחורי הבית = behind the house
• הוא עומד מאחור = He is standing in back / behind

So in your sentence, מאחורי is used because it is followed by הבית.

מעל means above / over.
על usually means on or on top of.

So:

• מעל המטבח = above the kitchen
• על המטבח would suggest something more like on the kitchen, which usually does not fit the intended meaning

A useful rule:

• על often suggests contact
• מעל does not necessarily suggest contact

The prefix ה־ is the Hebrew definite article, equivalent to English the.

• בית = house
• הבית = the house
• מטבח = kitchen
• המטבח = the kitchen

Unlike English, Hebrew usually adds the to the beginning of the noun instead of using a separate word.

Because they are indefinite here:

• חצר = a courtyard
• גג ישן = an old roof

If the sentence meant the courtyard and the old roof, it would be:

• החצר
• הגג הישן

So the sentence is introducing these things as existing there, not referring to already identified ones.

In Hebrew, adjectives normally come after the noun they describe.

• גג ישן = an old roof
• literally: roof old

This is one of the most important word-order differences from English.

Also, the adjective must agree with the noun in:

• gender
• number
• definiteness

Here both גג and ישן are masculine singular.

If the noun is definite, the adjective must also be definite.

So:

• גג ישן = an old roof
• הגג הישן = the old roof

This often surprises English speakers, because in English only the before the noun is enough. In Hebrew, both the noun and the adjective show definiteness.

Because the sentence has two separate existential clauses:

• מאחורי הבית יש חצר
• ומעל המטבח יש גג ישן

The prefix ו־ means and, but it does not replace יש. Hebrew normally repeats יש when each clause means there is / there are.

In Hebrew, ו־ means and, and it is usually written as a prefix attached to the following word.

So:

• מעל = above
• ומעל = and above

This is normal Hebrew spelling. Many small grammatical words are attached directly to the next word.

No. את is used before a definite direct object, but this sentence does not have a direct object.

Instead, the structure is:

• location phrase: מאחורי הבית / מעל המטבח
• existential word: יש
• thing that exists: חצר / גג ישן

So there is no place in this sentence where את would be used.