Mapacha hao hulala karibu na mama yao usiku.

In Swahili, demonstratives usually come after the noun, not before it. So the normal pattern is:

• mapacha hao = those twins

This is part of a broader pattern in Swahili: many modifiers come after the noun.

Hao is a demonstrative used for plural people. In context, it often means those, but it can also refer to people already mentioned, so it may feel like those twins or the twins in question.

It belongs to the same set as:

• huyo = that person / the person just mentioned
• hao = those people / the people just mentioned

Because mapacha refers to people. In Swahili, nouns referring to humans often take human/animate agreement, even if their shape looks like a different noun class.

So even though mapacha begins with ma-, it still takes the human demonstrative hao, not a non-human form like hayo.

Swahili does not have a separate word for the like English does. Definiteness is usually understood from:

• context
• word order
• demonstratives such as hao

So mapacha hao can naturally carry the sense of the twins or those twins without a separate article.

Hulala uses the hu- form, which usually gives a habitual or general meaning. It suggests something like:

• sleep habitually
• usually sleep
• sleep in general

So in this sentence, it sounds like a regular habit: this is what the twins do at night.

In this habitual form, hu- is the marker being used, and you do not add the usual subject marker like wa-.

Compare:

• hulala = sleep / usually sleep
• wanalala = are sleeping / are sleeping now / sleep, depending on context

So hulala is a normal complete verb form here.

Karibu na means near, close to, or next to.

The na is part of the expression when you say what something is near:

• karibu na mama yao = near their mother

This is important because karibu by itself can have other meanings too, such as welcome or nearby.

In mama yao, the possessive comes after the noun. The part -ao is what gives the meaning their, and yao is the form used here after mama.

So:

• mama yao = their mother

This is normal Swahili word order: noun + possessive.

Swahili often uses time words directly as adverbs, without a preposition. So usiku can simply mean:

• at night
• during the night

English needs at, but Swahili often does not.

The singular is pacha.

If you wanted to talk about one twin, you would use singular agreement, for example:

Pacha huyo hulala karibu na mama yake usiku.

The changes are:

• mapacha → pacha
• hao → huyo
• yao → yake

That gives the meaning That twin sleeps near his/her mother at night.