Rejaman itu cepat.

In Malay, demonstratives like ini (this) and itu (that) normally come after the noun:

• rumah itu = that house / the house
• orang ini = this person

So rejaman itu follows normal Malay word order. English puts that before the noun, but Malay puts itu after it.

Literally, itu means that. But in real usage, it often also makes the noun sound specific or already known, so in English it can sometimes be translated as the.

So rejaman itu cepat could be understood as:

• That smash is fast
• The smash is fast

Which English version is best depends on the context.

Malay often does not use a copula like English is/are when the predicate is an adjective.

So:

• Rejaman itu cepat = That smash is fast

This is completely normal Malay.
You do not need a separate word for is here.

Here, cepat is functioning as an adjective meaning fast/quick.

It describes the subject rejaman itu:

• Rejaman itu cepat = the smash is fast

Malay words can often be flexible, though. In another sentence, cepat can behave more like an adverb:

• Dia berlari cepat = He runs fast

So the same word can have different roles depending on the sentence.

Not in this sentence.

In Rejaman itu cepat, the structure is:

• Rejaman itu = the subject
• cepat = the predicate

So the meaning is The smash is fast, not just the fast smash.

This matters because English speakers often expect adjectives to sit inside the noun phrase. Here, cepat is not just attached to the noun; it is the main description being asserted about it.

The ending -an is a very common Malay suffix that often forms a noun.

In a word like rejaman, it helps create a noun referring to an action, event, or result related to the base word. So rejaman is a noun meaning something like a smash / a spike / a striking action, depending on context.

A useful general idea is:

• base word -> action/result noun with -an

You do not have to force one single rule for every word, but it is good to recognize -an as a common noun-forming suffix.

Normally, no. That sounds unnatural.

With adjectives like cepat, Malay usually just says:

• Rejaman itu cepat

The word adalah is not normally used before adjectives in everyday Malay.
English speakers often want to insert a word for is, but in this kind of sentence Malay simply does not need it.

You would usually say:

• Rejaman itu tidak cepat = That smash is not fast

Use tidak with adjectives and verbs.

Do not use bukan here.
Bukan is mainly used with nouns, identity statements, or contrast, not with an adjective like cepat.

No, not by itself.

Malay often does not mark tense directly in the sentence. Rejaman itu cepat simply states the quality, and the time is usually understood from context.

So depending on context, it could mean:

• The smash is fast
• The smash was fast

If needed, Malay can add time words such as:

• semalam = yesterday
• sekarang = now
• tadi = earlier

But the basic sentence itself does not force a tense the way English does.