Learn Hardcore Swahili: Mwanafunzi anayejifunza Kiswahili darasani leo atafurahi. - The student who is learning Swahili in the classroom today will be happy.

a- = subject prefix for he/she / the student (class 1, singular)
-na- = present tense marker (is/are doing)
-ye- = relative marker meaning who / that (is)
jifunza = verb stem meaning to learn / to study (reflexive form of funza)

So anayejifunza literally corresponds to something like:

a-na-ye-jifunza → he/she who is learning / the student who is learning

Could I also say mwanafunzi ambaye anajifunza Kiswahili… instead of anayejifunza? What is the difference?

Yes, you can. Both are correct and mean the same:

mwanafunzi anayejifunza Kiswahili…
mwanafunzi ambaye anajifunza Kiswahili…

Here:

ambaye = who / that (person who)
anayejifunza is basically a contracted form of ambaye anajifunza

In everyday Swahili:

The joined form (anayejifunza, anaoishi, wanaofanya, etc.) is very common and natural.
The ambaye + anafanya type is also correct, sometimes felt as slightly more explicit or careful, especially in teaching or very formal writing.

For a learner, it is useful to recognize both patterns as equivalent ways to form a relative clause about a person.

Why does the relative clause anayejifunza Kiswahili darasani leo come right after mwanafunzi?

In Swahili, a relative clause almost always comes immediately after the noun it describes.

mwanafunzi anayejifunza Kiswahili darasani leo
= the student who is learning Swahili in class today

If you put the relative clause somewhere else, it becomes confusing or ungrammatical. For example:

✗ mwanafunzi atafurahi anayejifunza Kiswahili… → wrong placement

Think of the pattern:

[NOUN] + [RELATIVE CLAUSE] + [REST OF THE SENTENCE]

So the structure is:

Mwanafunzi (noun)
anayejifunza Kiswahili darasani leo (relative clause describing the student)
atafurahi (main verb: will be happy)

Why is it darasani and not just darasa or katika darasa?

All three exist, but they have slightly different uses:

darasa = class / classroom (basic noun)
darasani = in class / in the classroom
- -ni at the end is a locative suffix, meaning in/at/on.
katika darasa = in the classroom, using the preposition katika
- noun.

In your sentence:

darasani is the most natural, compact way to say in class / in the classroom.
katika darasa would be understood, but it sounds a bit heavier; darasani is smoother and very common.

So:

anayejifunza Kiswahili darasani = who is learning Swahili in class.

What exactly does atafurahi mean, and how is it formed?

Atafurahi is a future tense verb:

a- = subject prefix for he/she / the student (class 1 singular)
-ta- = future tense marker (will)
furahi = verb stem be happy / rejoice

So:

atafurahi = he/she will be happy / the student will be happy

Compare with other tenses:

anafura(h)i → a-na-furahi = he/she is happy / is being happy (now)
alifurahi → a-li-furahi = he/she was happy / became happy (past)

Why is leo (today) placed before atafurahi? Could I move it?

In your sentence:

… darasani leo atafurahi.

Here leo sits at the end of the relative clause phrase and just before the main verb. This is very natural word order: place → time → main verb is common.

You can move leo, but the nuance can shift slightly:

Mwanafunzi anayejifunza Kiswahili darasani leo atafurahi.
- Most natural reading:
  The student who is learning Swahili in class *today will be happy.
  (*today mainly goes with the learning.)
Leo mwanafunzi anayejifunza Kiswahili darasani atafurahi.
- Today, the student who is learning Swahili in class will be happy.
  (leo emphasizes the whole event is happening today.)
Mwanafunzi anayejifunza Kiswahili darasani atafurahi leo.
- The student … will be happy *today.
  (*leo now naturally attaches more to atafurahi / being happy.)

All are grammatically fine; position subtly affects what leo is felt to modify or emphasize.

How would the sentence change if we talk about students (plural) instead of one student?

You need to change all the parts that agree with the noun:

mwanafunzi (singular) → wanafunzi (plural)
anayejifunza (he/she who is learning) → wanaojifunza (those who are learning)
atafurahi (he/she will be happy) → watafurahi (they will be happy)

So the plural version is:

Wanafunzi wanaojifunza Kiswahili darasani leo watafurahi.
= The students who are learning Swahili in class today will be happy.

Agreement pattern (class 2 / wa-):

Subject prefix: wa- (they)
Future marker: -ta-
Relative marker: -o- (for plural wa- often you just get wanao-)

Thus:

wanafunzi → wanao-jifunza → wata-furahi

Why is Kiswahili written with Ki- at the beginning and a capital letter?

Two points here:

The prefix Ki-
- Kiswahili belongs to noun class 7 (Ki-/Vi-).
- Many languages and tools / instruments / ways of doing things fall into this class.
- Roughly:
  - Waswahili = Swahili people (class 2, humans)
  - Kiswahili = the Swahili language (class 7)
So Ki- marks it as a thing / language, not a person.
Capital letter
- In modern writing, Kiswahili is usually capitalized, since it is the name of a language.
- You may also see it not capitalized (kiswahili) in more casual writing, but capitalizing is a good habit.

In the sentence, Kiswahili is simply the direct object of anayejifunza (who is learning Swahili). Swahili doesn’t add extra case marking to show that; the position plus verb meaning are enough.

What is the difference between jifunza and funza?

The difference is reflexive:

funza = to teach (someone else)
jifunza = to learn / to teach oneself

The ji- part is a reflexive element, meaning the action turns back on the subject.

Examples:

Nafunza Kiswahili.
I teach Swahili (to others).
Najifunza Kiswahili.
I am learning Swahili (myself).

So anayejifunza Kiswahili = who is learning Swahili (for themselves), which is the normal way to say someone is studying a subject.

Why does Swahili say mwanafunzi … atafurahi when a- already shows the subject? Isn’t that redundant?

In Swahili, the subject prefix on the verb is obligatory in normal sentences, even if the subject noun is already mentioned.

Mwanafunzi atafurahi.
Literally: Student he/she-will-be-happy.

The pattern is:

[Subject noun] + [verb with subject prefix]

The subject prefix:

Shows agreement (person, number, noun class).
Functions a bit like an attached pronoun.

You normally cannot drop the subject prefix:

✗ Mwanafunzi tafurahi → ungrammatical
✓ Mwanafunzi atafurahi

You can drop the noun mwanafunzi once it’s known from context and just say:

Atafurahi. = He/She will be happy.

But you cannot drop a- from atafurahi.

Should there be a comma before anayejifunza or before atafurahi, like in English?

In Swahili, commas are used much more sparingly than in English, and relative clauses like this usually do not take a comma.

Your sentence is best written simply as:

Mwanafunzi anayejifunza Kiswahili darasani leo atafurahi.

In English we often distinguish:

Restrictive clause: the student *who is learning Swahili will be happy* (no comma)
Non‑restrictive clause: the student, *who is learning Swahili, will be happy* (with commas)

Swahili typically doesn’t mark that difference with commas; the meaning is read from context, not punctuation. So no comma is necessary here.

How would you say “The student who is learning Swahili in class today will not be happy”?

You need to negate the future verb atafurahi.

The negative future uses ha- instead of the positive subject prefix:

a-ta-furahi → positive future (he/she will be happy)
ha-ta-furahi → negative future (he/she will not be happy)

So the full negative sentence is:

Mwanafunzi anayejifunza Kiswahili darasani leo hatafurahi.
= The student … will not be happy.

Breakdown of hatafurahi:

ha- = negative subject prefix for he/she / class 1
-ta- = future
furahi = be happy

Note that it is written as one word: hatafurahi, not ha tafurahi.