Learn Hardcore Hausa: Yau iyali na suna cikin gida gaba ɗaya. - Today my whole family is inside the house.

In Hausa, iyali is a collective noun (a group of people). Even though it looks like one word, it refers to several people, so it usually takes a plural verb:

Iyalina suna lafiya. – My family are well.
Iyali na suna cikin gida. – My family are in the house.

This is like British English: My family *are at home.
Using *suna matches the idea that the family is made up of multiple individuals.

What is the difference between iyali na and iyalina? Are both correct?

Grammatically they are the same: iyali + -na (my).

Written separate: iyali na
Written together: iyalina

They both mean my family. Many writers prefer joining noun + possessive: iyalina, gidana, motarka, etc., but you will see both joined and separated in real texts.

There is no real difference in meaning here; it’s mostly an orthography (spelling) choice.

What exactly does cikin mean, and how is cikin gida different from just a gida?

cikin comes from ciki (inside, stomach) and functions as a preposition in / inside.

cikin gida – in(side) the house
a gida – at home / in the house

Nuance:

cikin gida emphasizes inside the physical space of the house.
a gida is more general: “at home”, not necessarily stressing the interior.

In this sentence, suna cikin gida suggests physically in the house, but in everyday speech it overlaps a lot with suna a gida.

What does gaba ɗaya mean here, and what exactly is it modifying?

gaba ɗaya literally combines:

gaba – front, whole, entirety
ɗaya – one

Together gaba ɗaya means all / whole / entirely / as a whole.

In Yau iyali na suna cikin gida gaba ɗaya, it modifies iyali na:

gaba ɗaya = “all (of them)”, “the whole (family)”.

So: Today my whole family is in the house.

Where else can I put gaba ɗaya in the sentence, and does the meaning change?

You can move gaba ɗaya around a bit, with essentially the same meaning:

Yau gaba ɗayan iyali na suna cikin gida.
Yau duk iyali na suna cikin gida. (using duk, another “all” word)
Yau iyali na gaba ɗaya suna cikin gida.

All of these mean roughly: Today my whole family is at home.

Placing gaba ɗaya right after iyali na (or as gaba ɗayan iyali na) makes it clearer that “all” refers to the family, not to something else.

Could I say this sentence without cikin? For example: Yau iyali na suna gida gaba ɗaya. Is that correct?

Yes, that is also correct:

Yau iyali na suna gida gaba ɗaya.

Here gida works more like “home” than “house‑interior”.
Differences:

cikin gida – inside the house
gida – home / the house (less focus on inside)

In everyday speech both are common, and the meaning in context will usually be understood as “at home” either way.

Is suna here a present continuous “are (being)” or just a simple “are”?

Formally, suna is the 3rd person plural subject pronoun + imperfective (often called “present/progressive”) aspect. With a locative phrase like cikin gida, it usually means they are (currently) located…:

suna cikin gida – they are (right now) in the house
suna aiki – they are working

So in this sentence, suna is best understood as “are (now)”, not a habit:

Yau iyali na suna cikin gida – Today my family are at home (today, now).

If you remove yau, context will decide if it sounds like a habitual statement or a current situation.

Can yau appear somewhere else in the sentence, or must it be at the beginning?

It can move. Yau is an adverb of time (“today”), and Hausa is flexible with time adverbs. For example:

Yau iyali na suna cikin gida gaba ɗaya.
Iyalina suna cikin gida gaba ɗaya yau.
Iyalina yau suna cikin gida gaba ɗaya.

All are acceptable and mean Today my whole family is at home.
Starting with Yau is very common and sounds natural, like English “Today, my family…”.

Why don’t we use ne/ce (the copula) here, like Iyalina a cikin gida ne?

Hausa often uses subject + suna + locative to express “to be (located somewhere)”.

Iyalina suna cikin gida. – My family are in the house.

The copula ne/ce/ne‑ne/shine is mainly for equational or identificational sentences:

Wannan gida ne. – This is a house.
Shi likita ne. – He is a doctor.

You can say something like:

Iyalina suna cikin gida ne yau. (with a focus nuance: “It is today that my family are at home.”)

…but the basic, neutral way to say “are at home” here is with suna, not with ne/ce alone.

What is na doing here exactly? Is it the same na that links two nouns, like littafin malam?

No, in this sentence na is a possessive pronoun meaning my.

iyali na – my family
gidana – my house
motata – my car

The linker na (also na/ta) you see in phrases like littafin malam (“the teacher’s book”) is different; it agrees with gender/number and links two nouns:

littafin malam – the book of the teacher
gidan malam – the teacher’s house

Here, na is not that linker; it is the 1st person singular possessive (“my”).

If I drop na and just say Yau iyali suna cikin gida gaba ɗaya, what does it mean?

Without na, iyali is just family / families in general, not specifically my family.

Yau iyali suna cikin gida gaba ɗaya.
→ Today, families are all at home. / Today, the family (contextual one) is all at home.

Usually, if you mean my family, you keep na (or attach it: iyalina).
Context might make it clear, but grammatically, na is what marks possession.

Is there a different plural form of iyali, like iyalai? How does agreement work?

Yes, dictionaries often list:

iyali – one family
iyalai – families (plural)

But in practice, iyali behaves like a collective noun referring to a group of people, and in sentences like yours, it takes a plural verb:

Iyalina suna lafiya. – My family are well.
Iyalanmu suna gafara. – Our families are forgiving.

So in Yau iyali na suna cikin gida, suna is plural because the speaker is thinking of the family as “they”. If you truly needed “families” you could say iyalai (or iyalai da dama – many families), still with a plural verb.