Mwalimu alituonyesha tena kwamba herufi “m” ni konsonanti, lakini “o” ni irabu.

It is made of several pieces:

• a- = he/she (the subject marker for a singular person)
• -li- = past tense
• -tu- = us (object marker)
• -onyesha- = show
• -a = the final verb vowel

So alituonyesha means he/she showed us.

Because Swahili does not work like English he/she in many nouns.

Mwalimu just means teacher. It can refer to a man or a woman. The verb form a- also means he/she, not specifically one or the other.

You usually learn the person’s gender only from context, names, or extra words.

Swahili normally does not use articles like English a, an, or the.

So:

• mwalimu can mean a teacher or the teacher
• herufi can mean a letter or the letter

Context tells you which meaning is intended.

Tena means again.

So alituonyesha tena means showed us again.

Its position after the verb is very natural in Swahili. You may sometimes see adverbs moved for emphasis, but here this is the normal, straightforward order.

Kwamba means that and introduces the next clause.

So the structure is:

• Mwalimu alituonyesha tena kwamba...
• The teacher showed us again that...

Everything after kwamba is the thing being explained or stated.

Ni is the basic Swahili word for is/are in statements of identity or classification.

Here it is used twice because there are two separate statements:

• herufi m ni konsonanti
• o ni irabu

So each part needs its own ni.

Also, ni does not change for singular or plural the way English changes is/are. It stays ni.

Lakini means but.

It shows contrast between the two ideas:

• m is a consonant
• o is a vowel

So lakini is the right connector because the sentence is contrasting one letter with another.

Because Swahili often avoids repeating a word when the meaning is already clear.

The full version could be:

• herufi m ni konsonanti, lakini herufi o ni irabu

But repeating herufi is unnecessary, so the shorter version sounds natural:

• herufi m ni konsonanti, lakini o ni irabu

English does this too sometimes, as in the letter m is a consonant, but o is a vowel.

Herufi can be both singular and plural in form.

That is common with some Swahili nouns, especially loanwords. So:

• herufi = letter
• herufi = letters

Context and agreement show the difference. For example:

• herufi hii = this letter
• herufi hizi = these letters

In your sentence, it is singular because it refers to one specific letter: m.

When you talk about letters as things, Swahili treats them like noun-like items, just as English does.

So you can say:

• herufi m
• herufi o

and then describe them with ni:

• herufi m ni konsonanti
• o ni irabu

This is completely normal when discussing language, spelling, or the alphabet.

No. They are just noun words used after ni.

So:

• ni konsonanti = is a consonant
• ni irabu = is a vowel

There is no separate word for a before them, because Swahili does not normally use articles.

A simple guide:

• Mwalimu ≈ mwa-LEE-moo
• alituonyesha ≈ a-lee-too-on-YE-sha
• tena ≈ TEH-na
• kwamba ≈ KWAM-ba
• herufi ≈ heh-ROO-fee
• lakini ≈ la-KEE-nee
• irabu ≈ ee-RAH-boo
• konsonanti ≈ kon-so-NAN-tee

A few useful pronunciation notes:

• Swahili vowels are usually pure and consistent.
• e is always like e in bed (not like English ee).
• i is like ee in see.
• Stress is usually on the second-to-last syllable.