این صابون خوب است، اما شامپوی خواهرم از این بهتر است.

A very literal breakdown is:

• این = this
• صابون = soap
• خوب است = is good
• اما = but
• شامپوی = shampoo + linking sound/spelling
• خواهرم = my sister
• از این = than this
• بهتر است = is better

So the literal order is roughly:

This soap good is, but my sister’s shampoo than this better is.

That is normal Persian word order.

Persian usually does not use articles the way English does.

• There is no separate word for the.
• A/an can be shown with یک or sometimes with -ی, but it is often omitted if the meaning is clear.

So صابون can mean soap, a soap, or the soap, depending on context. Here این already makes it specific: this soap.

Because here خوب is not directly modifying the noun inside a noun phrase. It is the predicate of the sentence:

• این صابون خوب است = This soap is good

Persian often puts the adjective before the verb است in this kind of sentence.

If you wanted to say this good soap as a noun phrase, you would use ezafe:

• این صابونِ خوب = this good soap

So in your sentence, خوب means is good, not good soap.

Because there are two separate clauses:

• این صابون خوب است
• اما شامپوی خواهرم از این بهتر است

Each clause has its own verb است = is.

In careful written Persian, this is normal. In everyday speech, است is often shortened:

• خوب است → خوبه
• بهتر است → بهتره

In colloquial Persian, it is usually not pronounced as full است. Instead, it becomes a shorter spoken form:

• این صابون خوب است → این صابون خوبه
• از این بهتر است → از این بهتره

So it is not really disappearing completely; it is just changing to a more natural spoken form.

The two این words do different jobs:

• The first این modifies صابون: this soap
• The second این stands alone and means this one / this

So:

• این صابون = this soap
• از این بهتر = better than this / better than this one

Persian often avoids repeating the noun if it is already obvious.

خواهر means sister.

The ending -م means my.

So:

• خواهر = sister
• خواهرم = my sister

This is a very common Persian pattern:

• دوستم = my friend
• کتابم = my book
• برادرم = my brother

Because Persian is linking shampoo to my sister with the ezafe construction.

The base word is:

• شامپو = shampoo

To connect it to the next word, Persian uses ezafe. After a word ending in a vowel sound like شامپو, the ezafe is pronounced -ye and usually written with ی:

• شامپوی خواهرم = my sister’s shampoo

You can think of it as:

• shampoo-of my sister

Yes, از often means from, but in comparisons it also means than.

So:

• از تهران = from Tehran
• از این بهتر = better than this

This is a very common Persian pattern:

• بزرگ‌تر از = bigger than
• بهتر از = better than
• کم‌تر از = less than

So in this sentence, از این is not about movement; it is the comparison part.

Because Persian, like English, often leaves out repeated words when they are obvious.

So:

• شامپوی خواهرم از این بهتر است

really means:

• My sister’s shampoo is better than this soap

But Persian does not need to repeat صابون because the listener already knows what این refers to.

English does the same sometimes:

• This one is better than that
• You do not have to repeat soap every time.

بهتر is the normal and most common word for better in Persian.

So you should learn:

• خوب = good
• بهتر = better
• بهترین = best

A form like خوب‌تر can sometimes appear, but for ordinary better, بهتر is much more natural and standard.

اما is perfectly correct, but it sounds a bit more formal or written than everyday speech. In conversation, many speakers would more naturally use ولی.

A common spoken version would be:

• این صابون خوبه، ولی شامپوی خواهرم از این بهتره.

A careful pronunciation of the original sentence is roughly:

• in sâbun xub ast, ammâ shâmpu-ye xâharam az in behtar ast

And a more natural spoken pronunciation is:

• in sâbun khube, vali shâmpu-ye xâharam az in behtare