Learn Hardcore Swahili: Tunapaswa kushukuru kwa zawadi leo. - We should give thanks for the gift today.

So tunapaswa literally means we are required / we are supposed (to), which is usually translated as we should or sometimes we must, depending on context.

Is tunapaswa more like we should or we must in English? How strong is it?

Tunapaswa usually corresponds to English should – a recommendation, duty, or moral obligation, but not an absolute command.
However, in some contexts (for example, rules, laws, or strong expectations), it can feel close to we must or we are required to.

If you want to sound very strong, you might hear:

Lazima tushukuru kwa zawadi leo. – We must thank for the gift today. (more forceful than tunapaswa)

Why is it kushukuru and not tunashukuru after tunapaswa?

After verbs of obligation or ability (like kupaswa, kuweza, kujaribu), Swahili normally uses the infinitive form, which starts with ku-:

Tunapaswa kushukuru – We should thank / we should be thankful
Tunaweza kushukuru – We can thank / we are able to thank

If you say Tunashukuru kwa zawadi leo, that means We thank / We are thanking / We are grateful for the gift today (a statement of what is happening), not We should thank.
So tunapaswa kushukuru = we should thank, while tunashukuru = we (actually) thank.

What is the difference between kushukuru, asante, and shukrani? Can I say Tunapaswa asante kwa zawadi leo?

They belong to the same idea (thanks), but they behave differently:

kushukuru – verb: to thank / to be grateful
- Tunapaswa kushukuru – We should thank / be grateful.
asante – fixed expression / interjection: thank you
- Asante kwa zawadi. – Thank you for the gift.
shukrani – noun: thanks, gratitude
- Tunatoa shukrani kwa zawadi. – We give thanks for the gift.

You cannot say Tunapaswa asante kwa zawadi leo.
After tunapaswa you need a verb in the ku- form: kushukuru.

What does kwa mean in kushukuru kwa zawadi? Why not ya zawadi?

Here kwa shows the reason or cause of the thanking: for / because of the gift.

Common uses of kwa:

instrument: anaandika kwa kalamu – he writes with a pen
cause/reason: analia kwa uchungu – she cries from pain
purpose/benefit: nimekujia kwa ajili yako – I came for you / because of you

If you said shukrani ya zawadi, that would mean the thanks of the gift (a possessive relationship), which is not what we want here.
So kushukuru kwa zawadi is the natural way to say to be thankful for the gift.

Does zawadi mean “gift” or “gifts”? How do I know if it’s singular or plural here?

Zawadi belongs to the N-class of nouns, which usually have the same form in singular and plural.
So zawadi on its own can mean either a gift, the gift, gifts, or the gifts – the number is decided by context or by adding words like:

zawadi moja – one gift
zawadi nyingi – many gifts

In Tunapaswa kushukuru kwa zawadi leo, without extra context it could be understood as either for the gift or for the gifts.

Why is there no word for a or the before zawadi? How do I say the gift or a gift?

Swahili does not have articles like a, an, the.
The noun zawadi can cover all of these:

zawadi – a gift / the gift / gifts / the gifts (depending on context)

If you need to be more specific, you add other elements:

ile zawadi – that gift
zawadi ile uliyopata – that gift you received
zawadi moja – one gift (so it feels like a gift)

But normally you just say zawadi, and context tells you how to translate it into English.

Where can leo go in the sentence? Is it always at the end, as in Tunapaswa kushukuru kwa zawadi leo?

Time words like leo (today) are flexible. All of these are natural:

Leo tunapaswa kushukuru kwa zawadi.
Tunapaswa kushukuru kwa zawadi leo.

Putting leo at the beginning slightly emphasizes today:

Leo tunapaswa kushukuru kwa zawadi. – Today (in particular) we should thank for the gift.

Having leo at the end, as in the original sentence, is also very common and neutral.
Middle positions like Tunapaswa leo kushukuru kwa zawadi are understood but sound a bit less natural in everyday speech.

Who are we thanking here? The sentence doesn’t mention to whom we give thanks. How would I add that?

As written, Tunapaswa kushukuru kwa zawadi leo just says We should be thankful / give thanks for the gift today, without saying to whom.

To add the person, you normally attach an object marker to -shukuru or state the noun explicitly:

Tunapaswa kumshukuru Mungu kwa zawadi leo.
– We should thank God for the gift today.
Tunapaswa kumshukuru kwa zawadi leo.
– We should thank him/her for the gift today.

Here ku-m-shukuru is ku- (infinitive marker) + m- (object marker: him/her) + -shukuru (thank).

How would I say We should not thank / We shouldn’t be thankful for the gift today?

A common negative form of tunapaswa is hatupaswi:

Hatupaswi kushukuru kwa zawadi leo.
– We should not thank / We are not supposed to be thankful for the gift today.

So you keep kushukuru kwa zawadi leo the same and only change the verb of obligation to its negative (hatupaswi).

What tense or time does tunapaswa express? Is this about now or the future?

The -na- in tunapaswa is the present / near-future marker.
So tunapaswa usually refers to an obligation that exists now and typically includes the near future:

Right now, we are supposed to thank (today / soon).

If you want past or clear future, you change the tense marker:

Tulipaswa kushukuru kwa zawadi jana. – We were supposed to thank for the gift yesterday.
Tutapaswa kushukuru kwa zawadi kesho. – We will have to / will be required to thank for the gift tomorrow.

Why is the subject “we” not written separately as sisi? When would I use sisi?

In Swahili, the subject is normally shown by the prefix on the verb, so tu- in tunapaswa already means we.
That makes a separate sisi unnecessary in most sentences.

You add sisi mainly for emphasis or contrast:

Sisi tunapaswa kushukuru kwa zawadi leo, si wao.
– We are the ones who should thank for the gift today, not them.

Without emphasis, Tunapaswa kushukuru kwa zawadi leo is the natural form.