Leo tulijifunza nahau mpya, lakini fasili yake ilikuwa ngumu kidogo.

Tulijifunza can be broken down like this:

• tu- = we
• -li- = past tense
• jifunza = learn

So tulijifunza means we learned.

A very useful thing to know is that kujifunza means to learn, while kufunza means to teach / instruct. Historically, kujifunza is related to the idea of teaching oneself, which is why it has ji- in it.

So:

• tulijifunza = we learned
• tulifunza = we taught

That is a very important difference.

Leo means today.

In Swahili, time expressions very often come near the beginning of the sentence, especially when they set the scene for the whole statement. So:

• Leo tulijifunza... = Today we learned...

This is very natural word order in Swahili.

You could also hear time words in other positions, but putting Leo first is common and clear.

In Swahili, adjectives usually come after the noun they describe.

So:

• nahau mpya = new idiom

not:

• mpya nahau

That word order is one of the first big differences English speakers notice.

Also, the adjective usually agrees with the noun class. Here:

• nahau belongs to the N-class (class 9/10)
• -pya = new
• with the class prefix, it becomes mpya

So nahau mpya is the normal and correct order.

Nahau is one of those nouns whose singular and plural often look the same. It belongs to class 9/10, where this is very common.

So:

• nahau can mean idiom
• nahau can also mean idioms

You usually tell from context.

In this sentence, it is most naturally understood as singular, because the next part says fasili yake = its definition, referring back to one idiom.

Fasili yake means its definition.

Breakdown:

• fasili = definition
• yake = his / her / its in this noun-class pattern

A very important Swahili point: the possessive comes after the noun.

So:

• fasili yake = its definition
• literally, something like definition its

Also, the form yake agrees with fasili (the thing possessed), not with the English idea of it.

Ilikuwa means it was.

Breakdown:

• i- = subject marker for a class 9 noun
• -li- = past tense
• -kuwa = be

So:

• fasili ... ilikuwa ngumu = the definition ... was difficult

The subject here is fasili, and fasili is a class 9 noun, so the verb uses i-.

That is why you get:

• fasili ilikuwa... = the definition was...

not something like alikuwa or walikuwa, which would belong to other subject classes.

Ngumu means difficult / hard.

Kidogo means a little / somewhat.

Together:

• ngumu kidogo = a little difficult
• somewhat difficult
• a bit hard

Here kidogo softens the statement. It makes the sentence sound less absolute than just ngumu.

Compare:

• ilikuwa ngumu = it was difficult
• ilikuwa ngumu kidogo = it was a little difficult

So kidogo is acting a bit like an adverb here.

Yes, absolutely.

English speakers sometimes wonder about this because today feels present-time, but it is perfectly normal to say something like:

• Leo tulijifunza... = Today we learned...

This means the learning happened earlier today.

So there is no problem combining:

• Leo = today
• -li- = past tense

You are simply talking about an event that already happened during today.

Lakini means but.

It connects two ideas that contrast:

• Leo tulijifunza nahau mpya = Today we learned a new idiom
• lakini fasili yake ilikuwa ngumu kidogo = but its definition was a little difficult

So lakini works just like but in English, joining two clauses and showing contrast.

Yes. The sentence is a very nice example of normal Swahili clause order:

• Leo = time expression
• tulijifunza = verb
• nahau mpya = object + adjective
• lakini = connector
• fasili yake = new subject phrase
• ilikuwa ngumu kidogo = verb + description

So the overall flow is:

Time + action + object, but + subject + was + description

That makes it a very useful sentence for learning several common patterns at once:

• time at the beginning
• verb prefixes
• adjective after noun
• possessive after noun
• noun-class agreement on the verb