אני שומרת בשבילך מקום ליד החלון.

Because the speaker is feminine singular.

In Hebrew present tense, the verb form agrees with the subject in gender and number.
So:

• אני שומרת = I am keeping / saving / reserving — said by a woman
• אני שומר = I am keeping / saving / reserving — said by a man

Even though אני means I for both men and women, the present-tense verb shows the speaker’s gender.

It can mean any of those, depending on context.

Hebrew does not normally have a separate form for I keep versus I am keeping in the present tense. The form שומרת can cover:

• a general present meaning: I keep
• a progressive meaning: I am keeping
• this specific idiomatic meaning: I’m saving / reserving

In this sentence, because of מקום after it, שומרת מקום is understood as saving/reserving a place or seat.

Sometimes Hebrew drops subject pronouns, but here אני is helpful because the present-tense form does not show person clearly.

The form שומרת only tells you that the subject is feminine singular. By itself, it could mean:

• I am keeping
• you are keeping
• she is keeping

So adding אני makes it clear that the subject is I.

בשבילך means for you.

In this sentence, it shows who benefits from the action: the speaker is saving the place for you.

A very natural alternative in Hebrew is also:

• אני שומרת לך מקום ליד החלון

That also means I’m saving you a place by the window.

בשבילך can feel a little more explicit, like for your sake / on your behalf, though in many everyday situations both versions are natural.

In normal unpointed Hebrew spelling, בשבילך can be either:

• for you masculine singular
• for you feminine singular

The spelling stays the same, but the pronunciation changes:

• to a man: bishvilkha
• to a woman: bishvilekh

So from writing alone, you often need context to know which one is meant.

Because מקום is the normal word for place / spot / space, and in this context it naturally means a place to sit.

The expression לשמור מקום is very common and means:

• to save a place
• to save a spot
• naturally in English, often to save a seat

So even though מקום is broader than seat, it is exactly the right word here.

Because Hebrew has no indefinite article.

So:

• מקום = a place / a spot
• המקום = the place

Hebrew only marks definiteness with ה־ attached to the noun.

That is why מקום by itself can mean a place.

Because החלון means the window.

So:

• חלון = a window
• החלון = the window

In ליד החלון, the phrase means by the window / next to the window, usually referring to a specific window in the situation.

If you said ליד חלון, that would sound more like near a window, less specific.

ליד means next to, by, or near.

So:

• ליד החלון = by the window / next to the window

It is a separate preposition, not attached to the noun.

Hebrew word order is fairly flexible, and both are possible.

This sentence:

• אני שומרת בשבילך מקום ליד החלון

is very natural.

You could also hear:

• אני שומרת מקום בשבילך ליד החלון

That is also correct.

Putting בשבילך earlier can slightly emphasize for you. But in everyday speech, both orders are normal, and the meaning stays basically the same.

It can mean several related things.

The verb לשמור has a broad range of meanings, including:

• to keep
• to guard
• to watch over
• to preserve
• to save / reserve

So the exact meaning depends on context.

For example:

• אני שומרת על הילד = I’m watching the child
• אני שומרת את הקבלה = I’m keeping the receipt
• אני שומרת מקום = I’m saving a place / seat

Here, because the object is מקום, the meaning is clearly save/reserve.

Then שומרת would become שומר:

• אני שומר בשבילך מקום ליד החלון.

Everything else stays the same.

So the only change is the present-tense verb form, because it has to match the speaker’s gender.