Anak lelaki itu menangis sedikit kerana calar di dagunya terasa sakit.

Because lelaki by itself usually means man or male, often referring to an adult.
Anak lelaki literally means male child, so it fits boy much better.

Also, anak lelaki can sometimes mean son, depending on context. In this sentence, it is understood as the boy.

A very common alternative is budak lelaki, which also means boy.

Itu is a demonstrative word, usually meaning that, and sometimes it helps make the noun definite, like the in English.

Malay normally puts demonstratives after the noun:

• anak lelaki itu = that boy / the boy
• rumah itu = that house
• buku ini = this book

So the word order is normal Malay word order.

It can mean either, depending on context.

In many sentences, itu does not always need to be translated very literally as that. It often just shows that the speaker is talking about a specific, known person or thing. So anak lelaki itu can naturally be translated as the boy.

The basic root is tangis, which is related to crying.
The form menangis is the normal active verb meaning to cry or to weep.

In standard Malay, you usually need the verb form menangis in a sentence like this:

• Dia menangis. = He/She cried.

Using bare tangis here would not be normal standard sentence grammar.

Sedikit means a little, a bit, or slightly.

Here it modifies the verb menangis, so menangis sedikit means cried a little or cried a bit.

So it is functioning adverbially, even though sedikit is often introduced to learners as meaning little/small amount.

Yes. Kerana means because and is a standard, very common conjunction.

You could also use sebab, especially in more casual speech:

• ... kerana calar di dagunya terasa sakit
• ... sebab calar di dagunya terasa sakit

Both are natural.
Very roughly:

• kerana = a bit more standard/written
• sebab = often more conversational

Here, calar is a noun meaning scratch.

So calar di dagunya means the scratch on his chin.

If you want the verb to scratch, Malay often uses mencalar or another verb depending on context.

So in this sentence:

• calar = scratch, scrape mark
• calar di dagunya = the scratch on his chin

It has three parts:

• di = at / on / in
• dagu = chin
• -nya = his / her / its

So di dagunya means on his chin or at his chin.

A useful spelling point:

• di as a preposition is written separately: di dagunya
• di- as a passive verb prefix is written attached: dibuka, ditulis

That is a very common thing learners need to notice.

Yes. -nya is a third-person form that can mean:

• his
• her
• its

Malay does not mark gender the way English does.
So dagunya could mean his chin or her chin. In this sentence, context tells you it refers to the boy, so his chin is the natural translation.

Sometimes yes, but di dagunya is the more straightforward choice here for physical location.

For body parts, di often works well when you mean a concrete place:

• luka di tangan = a wound on the hand
• calar di dagu = a scratch on the chin

Pada is also possible in some contexts, but di feels more directly locational here.

Terasa comes from rasa and gives the idea of feeling or being felt, often in a noticeable or involuntary way.

So:

• sakit = painful / hurt
• terasa sakit = felt painful / felt sore / hurt

Using terasa sakit makes the sentence sound more natural and descriptive, because it focuses on the sensation coming from the scratch.

Very literally, calar di dagunya terasa sakit is something like:

the scratch on his chin felt painful

The phrase calar di dagunya is the subject of the clause, and terasa sakit is what is said about it.

So the structure is:

• calar di dagunya = the scratch on his chin
• terasa sakit = felt painful / hurt

Malay often allows this kind of structure very naturally:

• Kakinya sakit. = His leg hurts.
• Matanya terasa pedih. = His eyes feel sore.
• Calar di dagunya terasa sakit. = The scratch on his chin hurts.

Malay often does not need a verb like is/am/are where English does.

Also, in this sentence the predicate already contains a verb-like form: terasa. So Malay does not need anything extra between the subject and the description.

Compare:

• Dia marah. = He is angry.
• Rumah itu besar. = The house is big.
• Calar di dagunya terasa sakit. = The scratch on his chin feels painful.

So the absence of is is normal.

Malay does not have articles that work exactly like English a/an/the.

Instead, definiteness is shown by context or by words like ini and itu.

In this sentence:

• anak lelaki itu is definite because of itu
• calar di dagunya is understood from context as a specific scratch

So English needs the boy and the scratch, but Malay does not need separate article words for that.