Learn Hardcore Hausa: Da na sani cewa jarabawa za ta yi wuya, da na shirya da wuri. - If I had known that the exam would be hard, I would have prepared early.

So it is not the same as English “and” here, and not the same use as in phrases like da wuka (with a knife). In this type of sentence, Da + perfective verb introduces a condition that did not actually happen.

Why is da used twice: at the beginning and again before na shirya da wuri?

In Hausa, past unreal conditionals usually have da at the beginning of both clauses:

Da na sani... = If I had known... (the condition)
..., da na shirya da wuri. = ..., I would have prepared early. (the result)

So the structure is:

Da + [perfective clause], da + [perfective clause].

Both da’s work together to give the meaning: “If X had happened, Y would have happened.”

If you remove the second da, it becomes more like a simple sequence in the past, not clearly a counterfactual “would have” statement.

Could I use idan instead of da, like Idan na sani cewa jarabawa za ta yi wuya, zan shirya da wuri?

You can, but the meaning changes slightly:

Da na sani..., da na shirya...
→ strongly suggests a past unreal situation: If I had known, I would have prepared (but I didn’t).
Idan na sani cewa jarabawa za ta yi wuya, zan shirya da wuri.
→ more like a general / real condition: If I know (that) the exam will be hard, I will prepare early.

To talk about a regret about a past situation that didn’t happen, da... da... with perfective is the more natural pattern.
Idan is more general and is often used for real or open conditions, especially with za / zan for a future result.

Is na sani “I know” or “I knew/had known”? How does tense work here?

Na sani is the 1st person singular perfective of the verb sani (to know).

na = “I” (subject pronoun in perfective)
sani = know

Perfective in Hausa usually means a completed action and can be translated as past or present-perfect depending on context:

Na sani. = I know / I knew / I have known.

In combination with da for a counterfactual:

Da na sani... is naturally understood as “If I had known…” (a completed knowing in the past that did not actually happen).

What is the role of cewa in na sani cewa jarabawa za ta yi wuya?

Cewa is a complementizer, similar to English “that” introducing a clause:

na sani = I know
cewa jarabawa za ta yi wuya = that the exam will be hard

So the structure is:

na sani cewa + [clause]

In many cases, cewa could be dropped in casual speech and the meaning would still be clear:

Na sani jarabawa za ta yi wuya.

But including cewa is very common and stylistically smooth, especially in careful or written Hausa.

Why is it jarabawa za ta yi wuya and not something like za jarabawa yi wuya?

In Hausa, the typical order when you have za (future/irrealis marker) is:

[Subject] + za + [subject pronoun] + [verb phrase]

So:

jarabawa = the exam (subject, feminine)
za ta = will (she/it-fem)
yi wuya = be hard

Putting it together:

Jarabawa za ta yi wuya. = The exam will be hard.

You do not say za jarabawa yi wuya; za must come before the subject pronoun (here ta), and the full noun subject (jarabawa) usually comes before za or sometimes is repeated/clarified before or after, but the za + pronoun + verb core stays together.

Why do we need ta in jarabawa za ta yi wuya if we already said jarabawa?

In this construction, za always goes with a subject pronoun:

zan = za + ni (I will)
za ka = you (m.s.) will
za ta = she / it (fem.) will
za su = they will, etc.

So:

Jarabawa za ta yi wuya.

Here:

jarabawa = exam (a feminine noun)
ta = she / it (fem.) referring back to jarabawa

Many Hausa tenses/aspects work this way: even when you have a full noun as subject, the short pronoun (like ta) is still used in the verb phrase for agreement. So it’s not redundant; it’s part of normal Hausa verb grammar.

What does yi wuya literally mean, and why is yi used?

Literally:

yi = do
wuya = difficulty / hardship (also “neck” in other contexts)

The phrase yi wuya is an idiomatic verbal expression meaning “to be difficult / to be hard”:

Jarabawa za ta yi wuya.
= The exam will be difficult.

Hausa often uses yi + noun to express ideas that in English would use “to be + adjective.” Other examples:

yi kyau = to be beautiful / nice
yi sauƙi = to be easy

So wuya is not an adjective by itself; it combines with yi to make the “be hard” meaning.

What exactly does da wuri mean, and is this the same da as the first one?

Da wuri is an adverbial phrase meaning “early”:

da = with / in (preposition here)
wuri = place / time / early

So da wuri = early / in good time.

This da is not the same use as the conditional Da at the start of the sentence. They are the same word historically, but the functions are different:

First Da (sentence-initial) = conditional “if” (in past unreal construction).
da in da wuri = preposition forming an adverb (“early”).

Context and position tell you which function da has.

Could I say Da na sani jarabawa ta yi wuya, da na shirya da wuri instead of za ta yi wuya?

You could say something like Da na sani jarabawa za ta yi wuya... is the normal pattern.
If you changed it to ta yi wuya (without za), it would sound more like:

If I had known that the exam was hard (already), I would have prepared early.

Using za ta yi wuya makes it clear the hardness is expected / future relative to the time of knowing:

If I had known the exam would be hard, I would have prepared early.

So za ta keeps the nuance of “was going to be / would be hard” rather than “was already hard.”

Can any of the words da, na, or cewa be dropped without changing the meaning much?

The first da (conditional) and second da (result) are important for the counterfactual “If I had…, I would have…” meaning. Dropping them changes the feel or even the structure of the sentence.
The na before verbs (na sani, na shirya) is required, because it’s the subject pronoun “I” in perfective; without it, you don’t have a full finite verb (sani by itself is not a complete “I knew”).
Cewa can sometimes be omitted in speech:
- Na sani jarabawa za ta yi wuya. But keeping cewa is very natural and clear, especially for learners.

So practically: cewa is the only one that’s optional in some contexts; the da’s and na’s here are structurally important.

Is this sentence more formal or informal? Are there simpler alternative ways to say the same thing?

The sentence is standard and neutral; it fits both spoken and written Hausa. It’s not especially formal.

A slightly simpler but similar version could be:

Da na san jarabawa za ta yi wuya, da na shirya tun da wuri.

Changes:

san instead of sani (common spoken variant).
tun da wuri = “from early on / from the start,” another natural way to say “early.”

But your original sentence:

Da na sani cewa jarabawa za ta yi wuya, da na shirya da wuri.

is already clear, natural Hausa for:
If I had known that the exam would be hard, I would have prepared early.