Renjatan elektrik ialah bahaya besar.

Renjatan means shock or jolt, especially in a technical or medical sense. In renjatan elektrik, it means electric shock.

A native speaker might also say kejutan elektrik in some contexts, especially in less formal speech. Renjatan elektrik is correct and sounds a bit more formal or technical.

In Malay, the main noun usually comes first, and the word that describes or limits it comes after it.

So:

• renjatan elektrik = electric shock
  
  • renjatan = shock
  • elektrik = electric

This is different from English, where modifiers often come first.

Ialah is a linking word, similar to is/are in English in sentences that equate one thing with another.

So the structure is:

• Renjatan elektrik = subject
• ialah = linking word
• bahaya besar = complement

It is a fairly formal or standard way to say that X is Y.

This is a very common learner question.

A traditional grammar rule is:

• ialah comes before a noun phrase
• adalah comes before an adjective phrase or prepositional phrase

Here, bahaya besar is treated as a noun phrase:

• bahaya = danger
• besar = big/major

So ialah is the better standard choice:

• Renjatan elektrik ialah bahaya besar.

In everyday usage, native speakers do sometimes mix ialah and adalah, but if you want good standard Malay, ialah is preferred here.

Malay does not usually use articles like English a, an, or the.

So bahaya besar can mean:

• a major danger
• the major danger
• major danger

The exact interpretation depends on context. In this sentence, English would most naturally translate it as a major danger or simply a serious danger.

Because in Malay, adjectives usually come after the noun.

So:

• bahaya besar = big danger / major danger
• rumah besar = big house
• masalah serius = serious problem

English often puts the describing word first, but Malay usually puts it after the noun.

You could, but it would usually sound less natural here.

• bahaya besar = major danger
• satu bahaya besar = one major danger / a certain major danger

In general statements like this, Malay often leaves out satu. So:

• Renjatan elektrik ialah bahaya besar.
  is more natural than
• Renjatan elektrik ialah satu bahaya besar.

Using satu would add a slight sense of counting or emphasis.

Not exactly.

• bahaya besar = a major danger
  
  • this is a noun phrase
• sangat berbahaya = very dangerous
  
  • this is an adjective phrase

So:

• Renjatan elektrik ialah bahaya besar. = Electric shock is a major danger.
• Renjatan elektrik sangat berbahaya. = Electric shock is very dangerous.

Both are correct, but they are built differently and mean slightly different things.

Yes, it sounds a bit formal or written, especially because of ialah.

In everyday speech, a speaker might more naturally say:

• Renjatan elektrik sangat berbahaya.
• Renjatan elektrik memang bahaya.

But Renjatan elektrik ialah bahaya besar is still perfectly good Malay, especially in writing, safety notices, educational material, or formal explanation.

In some contexts, Malay can omit a linking verb more easily than English, especially in informal speech or headlines. But in a full standard sentence like this, ialah makes the relationship clear and grammatical.

So:

• Renjatan elektrik ialah bahaya besar. = clear, formal, standard
• Renjatan elektrik bahaya besar. = possible in very informal or compressed style, but less standard

For learners, it is better to keep ialah in a sentence like this.

A useful breakdown is:

• Renjatan elektrik = subject
• ialah = linking word
• bahaya besar = noun phrase describing the subject

So the pattern is:

[noun phrase] + ialah + [noun phrase]

This is a common formal Malay pattern for definitions and statements of identity, such as:

• Demam denggi ialah penyakit berbahaya.
• Air ialah keperluan asas.

It is a good sentence pattern to learn.