Vitabu vyangu vimo kwenye begi, na miwani yangu imo juu ya dawati.

Because Swahili possessives must agree with the noun class of the noun they describe.

• vitabu belongs to noun class 8, so -angu becomes vyangu
• miwani takes class 4 agreement, so -angu becomes yangu

So Swahili does not use one single form for my with every noun. The possessive changes to match the noun.

They are location forms meaning roughly are located / is located.

They are built from:

• a noun-class agreement prefix
• plus the locative ending -mo

So:

• vimo = vi-
  • -mo, agreeing with vitabu
• imo = i-
  • -mo, agreeing with miwani

In natural English, both are translated with are/is plus a place expression, but in Swahili the agreement is built into the word itself.

Because miwani is not a class 10 noun. It takes class 4 agreement.

That means:

• possessive: yangu
• subject/location agreement: i-, giving imo

This is a very common thing learners have to get used to: Swahili agreement follows the noun class of the Swahili noun, not what feels plural in English. Even though English says my glasses are, Swahili uses the agreement pattern that belongs to miwani.

In Swahili, possessives normally come after the noun they modify.

So:

• kitabu changu = my book
• vitabu vyangu = my books
• miwani yangu = my glasses

This is the normal word order. English puts my before the noun, but Swahili usually places the possessive after it.

They are two different kinds of location expressions.

• kwenye begi = in/on/at the bag, depending on context
  Here it naturally means in the bag
• juu ya dawati = on top of the desk

So juu ya is more specific: it clearly means on top of.

kwenye is a very common general locative word, while juu ya names a specific spatial relationship.

Because juu works like a relational noun meaning top or upper part.

So:

• juu ya dawati literally means something like the top of the desk
• in normal English, that becomes on the desk or on top of the desk

The ya links juu to the noun that follows it.

Because ni is usually used for identification or equivalence, not ordinary location.

For example:

• Huyu ni mwalimu = This is a teacher
• Kitabu hiki ni kizuri = This book is good
  (in some simple predicate patterns)

But for saying where something is, Swahili commonly uses locative forms like:

• vimo
• imo
• vipo
• ipo

So in this sentence, the idea is not X is Y, but X is located somewhere.

Very roughly:

• -mo = in there / within that place
• -po = there / at that specific place
• -ko = there / around there / located there

In careful explanations, these distinctions matter. In real-life speech, though, speakers often use them less strictly, and -po forms are especially common as general location forms.

So this sentence’s vimo fits well with in the bag, and imo is also acceptable in this kind of location statement.

The agreement would change to match noun class 7 singular.

So:

• kitabu changu kimo kwenye begi = my book is in the bag

Compare:

• kitabu → changu → kimo
• vitabu → vyangu → vimo

This is a good example of how noun class affects several words in the sentence at once.

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

So:

• begi can mean a bag or the bag
• dawati can mean a desk or the desk

Context tells you which meaning is intended. In this sentence, the translation makes it clear which English article sounds natural.