אני לא מאמינה שהקורס מתחיל כבר מחר, אבל אני מקווה שאהיה מוכנה.

Because the speaker is female.

In Hebrew, many verbs in the present tense change for gender in the singular:

• אני מאמין = I believe / I can’t believe (said by a male speaker)
• אני מאמינה = I believe / I can’t believe (said by a female speaker)

So in this sentence, אני לא מאמינה tells you the speaker is a woman. A man would say:

• אני לא מאמין שהקורס מתחיל כבר מחר, אבל אני מקווה שאהיה מוכן.

Notice that the last word would usually change too: מוכנה for a woman, מוכן for a man.

The prefix ש־ means that.

So:

• שהקורס מתחיל = that the course is starting / that the course starts

It is extremely common in Hebrew and is attached directly to the next word. In full, it comes from אשר, but in everyday Hebrew, ש־ is the normal form.

Examples:

• אני חושב שהוא צודק = I think that he is right
• אני יודעת שהיא כאן = I know that she is here
• אני מקווה שנצליח = I hope that we will succeed

So אני לא מאמינה שהקורס מתחיל... literally means I don’t believe that the course is starting...

Because Hebrew often uses the present tense for a planned or scheduled near-future event, just like English sometimes does.

Compare English:

• The course starts tomorrow.
• The train leaves at 8.

Those are present forms, but they refer to the future.

Hebrew does the same:

• הקורס מתחיל מחר = The course starts tomorrow
• הסרט מתחיל בשמונה = The movie starts at eight

So מתחיל is not strange here. It sounds natural because the course is something scheduled.

If you used the future tense יתחיל, that can also be possible in some contexts, but מתחיל מחר is very natural for timetabled events.

Because הקורס is a masculine noun.

In Hebrew, present-tense verbs agree in gender and number with the subject:

• masculine singular: מתחיל
• feminine singular: מתחילה
• masculine plural: מתחילים
• feminine plural: מתחילות

Since קורס is masculine, you say:

• הקורס מתחיל

If the subject were feminine, for example הכיתה or ההרצאה, you would say:

• הכיתה מתחילה מחר
• ההרצאה מתחילה מחר

Yes, כבר usually means already, but in this sentence it adds a feeling of surprise or suddenness.

So:

• הקורס מתחיל מחר = The course starts tomorrow
• הקורס מתחיל כבר מחר = The course starts already tomorrow / The course starts as early as tomorrow / The course starts tomorrow already

In natural English, you would usually not translate it word for word. Instead, it gives the idea:

• I can’t believe the course starts tomorrow already
• I can’t believe the course starts as soon as tomorrow

So כבר here emphasizes that tomorrow feels very soon.

Because מחר can function directly as an adverb of time, just like today or tomorrow in English.

So Hebrew simply says:

• מחר = tomorrow
• היום = today
• אתמול = yesterday

Examples:

• אני נוסע מחר = I’m traveling tomorrow
• היא באה היום = She is coming today
• ראיתי אותו אתמול = I saw him yesterday

You do not say a preposition equivalent to on tomorrow.

Both are possible, but they are slightly different structures.

In your sentence:

• אני מקווה שאהיה מוכנה = I hope that I will be ready

This is a full clause with:

• ש־ = that
• אהיה = I will be
• מוכנה = ready

Another possible form is:

• אני מקווה להיות מוכנה = I hope to be ready

That version uses an infinitive-like structure in English, but Hebrew often prefers the full clause with ש־ + future verb, especially in natural speech.

So the sentence as written is completely normal and very common.

אהיה is the first person singular future form of the verb להיות = to be.

So:

• אהיה = I will be

This verb is a bit irregular and very common, so it is worth memorizing.

Some future forms of להיות are:

• אהיה = I will be
• תהיה = you will be / she will be
• יהיה = he will be / it will be
• נהיה = we will be
• תהיו = you will be (plural)
• יהיו = they will be

In the sentence:

• אני מקווה שאהיה מוכנה

  the speaker says I hope that I will be ready.

Because it agrees with the speaker, who is female.

מוכן / מוכנה is an adjective meaning ready:

• מוכן = ready (masculine singular)
• מוכנה = ready (feminine singular)

Since the sentence uses מאמינה earlier, we know the speaker is female, so she also says:

• אהיה מוכנה = I will be ready (female speaker)

A male speaker would say:

• אהיה מוכן

This is very common in Hebrew: adjectives and many verb forms match the gender of the person speaking.

Because מוכנה is a predicate adjective, not a noun with the definite article.

In אהיה מוכנה, the word מוכנה describes the subject I:

• I will be ready

Predicate adjectives in Hebrew usually do not take ה־.

Compare:

• היא מוכנה = She is ready
• הוא עייף = He is tired
• אני שמחה = I am happy

But when an adjective directly modifies a noun and the noun is definite, the adjective usually also gets ה־:

• האישה המוכנה = the ready woman
• הילד העייף = the tired boy

So in your sentence, מוכנה is correct without ה־.

It is pronounced roughly she-eh-yeh.

It is made of:

• ש־ = that
• אהיה = I will be

When combined, it becomes:

• שאהיה

Learners often want to compress it too much, but it usually has three audible parts:

• she
• eh
• yeh

A rough guide for the whole sentence:

• Ani lo ma’amina sheha-kurs matchil kvar machar, aval ani mekava she-eh-yeh muchana.

The exact pronunciation depends on accent and speed, but that is a useful approximation.

Yes. Very often, אני לא מאמינה is used idiomatically to mean I can’t believe it.

Word for word, it is:

• אני = I
• לא = not
• מאמינה = believe

So literally: I don’t believe

But in context, especially with surprise, it often means:

• I can’t believe...
• I still can’t believe...

So the Hebrew expression is very natural even if the English translation is slightly less literal.

It is not always strictly necessary, but it is very natural and often preferred.

You could say:

• אני לא מאמינה שהקורס מתחיל כבר מחר, אבל מקווה שאהיה מוכנה.

People may say this in casual speech, but it sounds more complete and standard to repeat the subject:

• אבל אני מקווה שאהיה מוכנה

Repeating אני makes the clause clear and balanced, especially in writing.

So the sentence as given sounds natural and standard.

The sentence follows a very normal Hebrew order:

• אני לא מאמינה = I don’t believe
• שהקורס מתחיל כבר מחר = that the course starts already tomorrow
• אבל = but
• אני מקווה = I hope
• שאהיה מוכנה = that I will be ready

So the overall structure is:

I don’t believe + that-clause, but I hope + that-clause

This is very similar to English in this case, which makes the sentence relatively learner-friendly. The main things to notice are the Hebrew agreement patterns and the use of present tense for a scheduled future event.