השמלה הזאת לא מתאימה לי, אבל החצאית הזאת כן מתאימה לי.

In Hebrew, demonstratives like this usually come after the noun.

So:

• השמלה הזאת = this dress
• החצאית הזאת = this skirt

This is the normal Hebrew pattern:

• הספר הזה = this book
• הילדה הזאת = this girl

So even though English says this dress, Hebrew says literally the dress this.

Because in Hebrew, when you say this/that + noun, both parts are typically marked as definite.

So:

• שמלה = a dress
• השמלה הזאת = this dress

And similarly:

• חצאית = a skirt
• החצאית הזאת = this skirt

This double definiteness is normal in modern Hebrew:

• הבית הזה = this house
• המכונית הזאת = this car

Because שמלה and חצאית are feminine singular nouns, and the demonstrative has to match their gender.

• masculine singular: זה
• feminine singular: זאת

So:

• הספר הזה = this book (masculine)
• השמלה הזאת = this dress (feminine)

Both שמלה and חצאית are feminine, so זאת is the correct form.

Because the verb/adjective-like form מתאים / מתאימה must agree with the subject in gender and number.

Here, the subjects are:

• השמלה — feminine singular
• החצאית — feminine singular

So the correct form is מתאימה.

Compare:

• הספר מתאים לי = The book suits me / fits me (masculine)
• השמלה מתאימה לי = The dress suits me / fits me (feminine)

If the noun were masculine, you would use מתאים.

לי means to me or for me, depending on the context.

It is made from:

• ל־ = to / for
• י = me

So:

• מתאימה לי literally means something like is suitable to me / for me
• in natural English: fits me or suits me

Other examples:

• לו = to him
• לה = to her
• לנו = to us

So you could also say:

• השמלה מתאימה לה = The dress suits her

לא is the standard Hebrew word for not.

So:

• לא מתאימה לי = doesn’t suit me / doesn’t fit me

Hebrew usually puts לא directly before the verb or predicate it negates.

Compare:

• אני לא יודע = I don’t know
• זה לא טוב = That isn’t good
• השמלה הזאת לא מתאימה לי = This dress doesn’t suit me

It does mean yes, but in sentences like this it often works as a contrast word: yes / actually / does.

In your sentence:

• ...אבל החצאית הזאת כן מתאימה לי

the כן emphasizes the contrast with the earlier negative statement:

• The dress doesn’t suit me, but the skirt does suit me.

So here כן is like the English stress on does:

• does fit me
• actually does suit me

This use of כן is very common after a negative statement.

Yes, sometimes it can be omitted if the meaning is obvious from context.

For example, in conversation you might hear:

• השמלה הזאת לא מתאימה לי, אבל החצאית הזאת כן.

That means:

• This dress doesn’t suit me, but this skirt does.

However, the full version:

• ...אבל החצאית הזאת כן מתאימה לי

is very clear and completely natural. Hebrew often keeps the repeated words, especially in learner-friendly or careful speech.

It can mean several related things, depending on context:

• fits physically
• suits someone stylistically
• is suitable / appropriate

So in this sentence, מתאימה לי could mean:

• the dress does not fit me well
• the dress does not suit me
• the skirt works for me better

The exact nuance depends on the situation.

Examples:

• החולצה הזאת לא מתאימה לי
  could mean This shirt doesn’t fit me or This shirt doesn’t suit me.

• השעה הזאת לא מתאימה לי
  means That time doesn’t work for me.

So מתאים is a very flexible word.

אבל means but.

It connects the two contrasting parts of the sentence:

• The dress doesn’t suit me
• but the skirt does

It is the most common everyday word for but in Hebrew.

Example:

• אני עייף, אבל אני עובד. = I’m tired, but I’m working.

So in your sentence, אבל introduces the contrast between the dress and the skirt.

A natural pronunciation would be approximately:

ha-sim-LA ha-ZOT lo mat-i-MA li, a-VAL ha-kha-TSA-it ha-ZOT ken mat-i-MA li

A few notes:

• השמלה = ha-simla
• הזאת = ha-zot
• מתאימה = mat'ima or mati'ma, depending on how carefully someone speaks
• חצאית = khatsa'it or khatsait

The ח in חצאית is a throatier sound than English h. Many learners find that word tricky at first.

Yes. In modern Hebrew, both זאת and זו can mean this for feminine singular.

So you may see:

• השמלה הזאת
• השמלה הזו

Both are correct.

Very roughly:

• הזאת often sounds a bit fuller or slightly more formal/careful
• הזו is also very common in everyday Hebrew

In your sentence, הזאת is completely standard.

The structure is:

[noun phrase] + [not / yes] + [predicate] + [to me]

So:

• השמלה הזאת = subject/topic
• לא מתאימה לי = does not suit me

and then:

• אבל החצאית הזאת = but this skirt
• כן מתאימה לי = does suit me

Hebrew often builds sentences this way when comparing two things:

• X לא..., אבל Y כן...
• X doesn’t..., but Y does...

That pattern is very common and useful.