Bibi husimulia hadithi za ajabu mara kwa mara usiku.

hu- marks a habitual action in Swahili. It shows that something happens regularly, usually, or as a repeated habit.

So husimulia means something like usually tells or habitually narrates, not just is telling right now.

A useful contrast is:

• anasimulia = is telling / is narrating (often current or ongoing)
• husimulia = usually tells / regularly narrates

With the habitual hu- form, Swahili commonly uses hu- directly before the verb stem, without adding the normal subject marker such as a-.

So you get:

• Bibi husimulia
• not Bibi ahusimulia

The subject is already clear from bibi, so the sentence is perfectly normal as it is.

The dictionary form is kusimulia, meaning to tell, to narrate, or to recount.

In Swahili dictionaries, verbs are usually listed with ku-, which is the infinitive marker:

• kusimulia = to narrate
• hu-simulia = usually narrates

So ku- is the infinitive form, and hu- is the habitual marker.

Because hadithi is one of those Swahili nouns whose singular and plural forms are identical.

So:

• hadithi can mean story
• hadithi can also mean stories

You tell whether it is singular or plural from the agreement words around it. In this sentence, za shows plural agreement, so hadithi is understood as stories here.

za is a connector that links the noun to what describes it. It is often taught as meaning something like of or as part of an adjective-like structure.

So:

• hadithi za ajabu = literally something like stories of wonder/strangeness
• natural English meaning: amazing stories, strange stories, or wonderful stories, depending on context

The important point is that za agrees with the noun class of hadithi in the plural.

Compare:

• kitabu cha ajabu = a strange/amazing book
• vitabu vya ajabu = strange/amazing books
• hadithi za ajabu = strange/amazing stories

Because ajabu often behaves like an unchanging descriptive word in expressions like this. The agreement is shown by za, while ajabu itself stays the same.

So the grammar signal is carried by:

• za = agreement with hadithi

while:

• ajabu stays ajabu

This is normal and very common in Swahili.

It can mean several related things, depending on context:

• strange
• surprising
• astonishing
• amazing
• sometimes wonderful

So hadithi za ajabu could be understood as:

• strange stories
• amazing stories
• wonderful tales

All of those are possible shades of meaning.

Yes, mara kwa mara is a very common idiomatic expression. It means:

• often
• repeatedly
• regularly
• from time to time

The word mara means time or occasion, and the full phrase has the sense of something happening again and again.

So it is best learned as a fixed expression: mara kwa mara.

Swahili often uses time words directly, without a preposition.

So you can simply say:

• usiku = at night / during the night
• asubuhi = in the morning
• mchana = during the day
• jioni = in the evening

English needs at night, but Swahili does not need a separate word for at here.

That is a natural place for a time expression in Swahili. The sentence follows a very common order:

• Subject: Bibi
• Verb: husimulia
• Object: hadithi za ajabu
• Adverbial expressions: mara kwa mara usiku

Putting usiku at the end sounds natural and clear. Swahili word order is somewhat flexible, but this order is very normal.

Yes. Swahili allows some flexibility, especially with time expressions.

For example:

• Usiku, bibi husimulia hadithi za ajabu mara kwa mara.

That gives a little more emphasis to at night. The original order is still perfectly natural; moving it just changes the focus slightly.

Not always. Bibi can mean:

• grandmother
• old woman
• elderly lady
• sometimes a respectful lady / madam, depending on context

In many learning sentences, it is understood as grandmother, but the exact meaning depends on who the speaker is talking about.

Because Swahili generally does not use articles like English the and a/an.

So a noun like bibi can mean:

• a grandmother
• the grandmother
• simply grandmother

The exact meaning comes from context, not from an article.

The same is true for hadithi:

• a story
• the story
• stories
• the stories

Context tells you which one is intended.