אם את עצבנית מדי עכשיו, אל תלכי להתקלח מיד; תשבי רגע ותשתי מים.

Because the speaker is talking to one female person.

In Hebrew, adjectives and many verb forms agree with the person being addressed. So:

• את = you (feminine singular)
• עצבנית = upset / nervous / irritable (feminine singular)
• תלכי, תשבי, תשתי = 2nd person feminine singular verb forms

If you were speaking to a man, you would say:

אם אתה עצבני מדי עכשיו, אל תלך להתקלח מיד; תשב רגע ותשתה מים.

In present-tense Hebrew, the verb to be is usually not stated.

So את עצבנית literally looks like you upset, but it means you are upset.

The pronoun את is the subject, and עצבנית is the adjective describing the subject. Hebrew simply leaves out are in this kind of sentence.

עצבנית can mean nervous, agitated, irritable, or worked up, depending on context.

In this sentence, it probably does not mean calm clinical nervousness. It sounds more like:

• agitated
• upset
• worked up
• too irritated

So the idea is: if you are too emotionally stirred up right now, do not go shower immediately.

מדי means too or overly.

In Hebrew, מדי usually comes after the adjective or adverb it modifies:

• חם מדי = too hot
• יקר מדי = too expensive
• עצבנית מדי = too upset / too irritable

So עצבנית מדי is the normal word order.

אם means if.

So אם את עצבנית מדי עכשיו means if you are too upset right now.

A learner should also know that אם is spelled the same as the word for mother only in writing without vowels, but they are pronounced differently:

• אִם = if
• אֵם = mother

Because Hebrew normally forms a negative command with אל + future form.

So:

• אל תלכי = don’t go
• אל תשבי = don’t sit
• אל תשתי = don’t drink

By contrast, לא תלכי usually means you will not go or you won’t go, not a direct command.

So here אל תלכי is the correct way to say don’t go take a shower.

In Modern Hebrew, the future tense is very often used to give instructions or commands, especially in everyday speech.

So these pairs are both possible:

• שבי / תשבי = sit
• שתי / תשתי = drink

The future forms can sound a little more neutral, less abrupt, or more conversational. So תשבי רגע ותשתי מים is very natural spoken Hebrew.

להתקלח means to shower or to take a shower.

It is the infinitive form, and it belongs to the התפעל pattern, which often has a reflexive or self-directed meaning. In practice, though, you can just learn להתקלח as the normal verb for to shower.

After verbs like ללכת (to go), Hebrew often uses an infinitive to express purpose:

• ללכת לאכול = to go eat
• ללכת לישון = to go to sleep
• ללכת להתקלח = to go take a shower

So אל תלכי להתקלח מיד literally means don’t go to shower immediately, i.e. don’t go take a shower right away.

מיד means immediately, right away, or at once.

So:

• אל תלכי להתקלח מיד = don’t go shower immediately
• מיד adds the idea of doing it right now without waiting

Its placement at the end is normal and natural.

רגע literally means a moment.

In this sentence, תשבי רגע means:

• sit for a moment
• sit down for a second
• wait a bit and sit

This is a very common everyday use of רגע in Hebrew. It often softens the instruction and makes it sound more natural.

The ו־ is simply the Hebrew word and, attached as a prefix.

So:

• תשבי = sit
• ותשתי = and drink

Hebrew very often attaches ו־ directly to the next word instead of writing a separate word for and.

No. They are two different words that happen to be spelled the same.

Here, את is the subject pronoun meaning you (feminine singular):

• אם את עצבנית = if you are upset

But Hebrew also has את as the direct-object marker, used before a definite direct object:

• אני שותה את המים = I am drinking the water

That is why there is no object-marker את before מים in your sentence: מים here is just water in a general sense, not the water.

For a man:

אם אתה עצבני מדי עכשיו, אל תלך להתקלח מיד; תשב רגע ותשתה מים.

For a group of women:

אם אתן עצבניות מדי עכשיו, אל תלכו להתקלח מיד; תשבו רגע ותשתו מים.

For a group of men or a mixed group:

אם אתם עצבניים מדי עכשיו, אל תלכו להתקלח מיד; תשבו רגע ותשתו מים.

This is a good example of how Hebrew changes pronouns, adjectives, and verbs to match gender and number.