Basi lililojaa watu linaenda mjini.

Because basi is treated as a singular noun in noun class 5, and class 5 uses li- for agreement.

So the sentence shows agreement with basi in two places:

• li-li-lo-jaa = that is/full of
• li-na-enda = is going / goes

If the noun were plural, the agreement would change. For example:

• mabasi yaliyojaa watu yanaenda mjini = buses full of people are going to town

So li- is not part of the meaning bus itself; it is the agreement marker that matches basi.

lililojaa packs several pieces into one word:

• li- = agreement with basi (class 5)
• -li- = past/completive-type marker
• -lo- = relative marker for class 5, meaning something like that/which
• -jaa = verb root from kujaa, to become full / be full

So literally it is something like:

• li-li-lo-jaa = that which became full

In natural English, that usually comes out as:

• that is full
• which is full
• full of

A very common learner reaction is: “Why is so much packed into one word?” That is just very normal Swahili structure, especially in relative clauses.

Because the sentence needs a form that modifies the noun basi.

Compare:

• Basi limejaa watu.
  = The bus is full of people.
  This is a complete sentence.

• Basi lililojaa watu linaenda mjini.
  = The bus that is full of people is going to town.
  Here, lililojaa watu describes which bus we mean.

So:

• limejaa = predicate in a full sentence
• lililojaa = relative form attached to a noun

English often uses that is full of people or simply full of people. Swahili commonly uses this relative verb form.

Because with kujaa, Swahili often puts the thing that fills something directly after the verb.

So:

• kujaa watu = to be full of people
• kujaa maji = to be full of water

English needs of, but Swahili usually does not here.

So watu is the complement telling you what it is full of.

linaenda breaks down like this:

• li- = class 5 subject marker, agreeing with basi
• -na- = present tense marker
• enda = verb stem go

So linaenda means:

• is going
• goes

The exact English choice depends on context.

As for kwenda: the dictionary form is kwenda (to go), but when conjugated, the infinitive prefix ku- is removed, leaving the stem enda. So:

• kwenda → linaenda

That is normal.

Because -ni is a locative ending.

• mji = town / city
• mjini = in town / to town / at the town

With a verb of motion like -enda (go), mjini usually means to town or to the city.

So Swahili often uses a locative form where English uses a preposition plus a noun.

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

So basi can mean:

• a bus
• the bus

The context tells you which one is meant.

That is why a Swahili sentence can be translated in more than one natural English way depending on the situation.

A natural plural version is:

• Mabasi yaliyojaa watu yanaenda mjini.

The changes are:

• basi → mabasi = bus → buses
• li- agreement → ya- agreement
• -lo- relative marker → -yo-

So:

• lililojaa → yaliyojaa
• linaenda → yanaenda

This is a good way to see how important noun-class agreement is in Swahili.