Relative clauses connect a noun to extra information using forms of koji/koja/koje. The relative pronoun agrees with the noun in gender/number, and its case depends on its role inside the clause.
Learn when to use koji, kojeg/koju, and kojem/kojoj in real Bosnian sentences.
A relative clause adds extra information about a person or thing: "the woman who lives here", "the book that I bought".
In Bosnian, the linking word changes form. You choose a form of koji depending on agreement and case.
Think in two steps: first choose who/what the clause describes, then choose the case required inside the clause.