Questions & Answers about Kitabu changu ni tofauti na kitabu cha Juma.
Because kitabu belongs to the ki-/vi- noun class, and possessives must agree with the noun class.
- kitabu = book
- changu = my, agreeing with a ki- class noun
So:
- kitabu changu = my book
If you used yangu, that would be the possessive form used with a different noun class, so it would not match kitabu.
In Swahili, possession is often expressed with -a plus a form that agrees with the noun being possessed.
Since kitabu is in the ki-/vi- class, the possessive linker becomes cha:
- kitabu cha Juma = Juma's book / the book of Juma
So cha here does not mean of all by itself in every situation; it is the agreement form of the possessive connector for this noun class.
Compare:
- kitabu cha Juma = Juma's book
- vitabu vya Juma = Juma's books
The connector changes with the noun class.