אני מכינה קפה לכולם.

Because the speaker is female.

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

• מכין = masculine singular
• מכינה = feminine singular

So:

• אני מכינה = I am making/preparing, said by a woman
• אני מכין = I am making/preparing, said by a man

It would be:

אני מכין קפה לכולם.

The only change is:

• מכינה → מכין

Everything else stays the same.

מכינה is the feminine singular present-tense form of להכין, which means to prepare or to make.

So מכינה can mean:

• prepares
• is preparing
• am preparing
  depending on context

In this sentence, it means am making/preparing.

Yes.

Hebrew present tense often covers both:

• simple present: I make
• present progressive: I am making

So אני מכינה קפה לכולם could mean either:

• I make coffee for everyone
• I am making coffee for everyone

Context tells you which meaning is intended.

Because Hebrew usually does not use a present-tense form of to be the way English does.

English says:

• I am making

Hebrew simply says:

• אני מכינה

So in present-tense sentences, Hebrew often leaves out a separate word like am / is / are.

לכולם means for everyone or sometimes to everyone, depending on context.

It is made of:

• ל־ = to / for
• כולם = everyone / all of them

So:

• לכולם = to/for everyone

In this sentence, for everyone is the most natural translation:

• אני מכינה קפה לכולם = I am making coffee for everyone

Sometimes, but here it is often useful to keep it.

In Hebrew, subject pronouns are sometimes omitted when the subject is clear from context. But in the present tense, the verb usually shows only gender and number, not person clearly enough.

For example, מכינה could mean:

• I am preparing
• you are preparing (to one female)
• she is preparing

So אני helps make it clear that the subject is I.

This is a very normal Hebrew word order:

• אני = subject
• מכינה = verb
• קפה = object
• לכולם = for everyone

So the structure is basically:

subject + verb + object + indirect object / prepositional phrase

Hebrew can sometimes move things around for emphasis, but this order is natural and standard.

קפה is usually treated as masculine in modern Hebrew.

For example:

• קפה חם = hot coffee
  not קפה חמה

In this sentence, you do not see its gender directly, because there is no adjective attached to קפה.

A common pronunciation is:

ani mekhina kafe lekulam

Word by word:

• אני = ani
• מכינה = mekhina
• קפה = kafe
• לכולם = lekulam

The kh sound in mekhina is like the Hebrew letter כ/ח, not like a normal English k.