Saya sangka meja itu baik, rupanya meja itu kemik.

Sangka means to think / to assume / to suppose, often when your belief later turns out to be wrong.

In this sentence, Saya sangka... rupanya... is a very common pattern:

• Saya sangka... = I thought...
• rupanya... = it turns out... / apparently...

So sangka fits especially well because the speaker is correcting an earlier assumption.

Fikir also means to think, but it is broader and often refers to the process of thinking, considering, or having an opinion.
So:

• Saya fikir... = I think / I thought
• Saya sangka... = I assumed / I thought, but I was mistaken

Rupanya is used when the true situation is revealed, often after a mistaken belief.

In this sentence, it means something like:

• turns out
• apparently
• as it turns out

It often introduces a contrast between expectation and reality.

Example pattern:

• Saya sangka A, rupanya B.
  = I thought A, but it turned out to be B.

So here, rupanya signals the correction of the speaker’s first impression.

Malay often repeats nouns where English would prefer a pronoun like it.

So:

• Saya sangka meja itu baik, rupanya meja itu kemik.

sounds natural in Malay, even though English might more naturally say:

• I thought the table was fine, but it turned out to be dented.

Malay does have pronouns, but repeating the noun is very common and often clearer.

A shorter version is also possible in some contexts:

• Saya sangka meja itu baik, rupanya kemik.

That can work if the context is already clear, but repeating meja itu is perfectly normal.

Itu means that.

So:

• meja = table
• meja itu = that table / the table

In Malay, demonstratives like ini and itu usually come after the noun:

• meja ini = this table
• meja itu = that table

This is different from English, where this and that come before the noun.

Also, in many contexts, meja itu can sound like the table, not only that table, depending on context.

Yes, baik can mean good, but for objects it often means something like:

• in good condition
• fine
• okay
• not damaged

So in this sentence, meja itu baik probably means the speaker thought the table was in good shape.

That said, for physical condition, Malay speakers might also use words that are more specific, such as:

• elok = in good condition / nice / proper
• bagus = good / excellent
• tidak rosak = not broken / not damaged

So baik is understandable, but depending on context, some speakers may prefer a more specific adjective.

Kemik means dented or caved in, usually because something has been pressed or hit.

It is commonly used for physical damage to objects, especially metal or surfaces.

Examples:

• Kereta itu kemik. = The car is dented.
• Tin itu kemik. = The can is dented.

For a table, kemik suggests that part of it is pushed in or damaged rather than simply scratched.

Malay often does not need a separate word for but when the contrast is already clear from context.

In this sentence, the contrast comes from:

• Saya sangka... = I thought...
• rupanya... = it turns out...

That combination already implies but actually.

So:

• Saya sangka meja itu baik, rupanya meja itu kemik.

naturally means:

• I thought the table was fine, but it turned out to be dented.

If you added a word like tetapi, it would usually sound unnecessary here.

Yes. The sentence follows normal Malay word order.

Breakdown:

• Saya = I
• sangka = thought / assumed
• meja itu = that table
• baik = good / fine
• rupanya = turns out
• meja itu = that table
• kemik = dented

Malay generally uses:

• Subject + verb + object/complement

So:

• Saya sangka meja itu baik
  literally: I thought table that good

This is normal Malay structure.

Yes, that is a very natural translation.

Because baik here probably refers to condition, okay, fine, or in good condition may sound more natural in English than simply good.

Possible natural translations:

• I thought the table was fine, but it turned out to be dented.
• I thought the table was in good condition, but it turned out to be dented.
• I thought the table was okay, but it turned out to be dented.

All of these match the Malay sentence well.

Yes. Rupanya can also literally relate to appearance / looks / form in some contexts, because it comes from rupa, which is connected to appearance or form.

But in everyday sentence patterns like this one, rupanya very commonly means:

• it turns out
• apparently
• so actually

So in your sentence, you should understand it as a discourse marker showing that the truth is different from what was first believed, not as a literal word about appearance.

Yes. Some possible shorter or more conversational versions are:

• Saya sangka meja itu elok, rupanya kemik.
• Saya ingat meja itu elok, rupanya kemik.
• Ingatkan meja itu elok, rupanya kemik.

Notes:

• ingat or ingatkan can also be used for thought / assumed
• elok may sound more natural than baik for physical condition
• Dropping the second meja itu is common when the meaning is obvious

So the original sentence is understandable and grammatical, but everyday speech may use a slightly different wording.