Ali'ye bir mektup yazdım.
English: I wrote a letter to Ali.
The 'dolaylı nesne' in Turkish is the indirect object of a sentence. It shows to whom or for whom an action is done, usually marked with the '-e/-a' ending (dative case).
Use the dolaylı nesne in Turkish when you want to indicate the person or thing that receives the result of an action indirectly. Common with verbs like 'vermek' (to give), 'göndermek' (to send), 'anlatmak' (to explain), and 'sormak' (to ask).
Ali'ye bir mektup yazdım.
English: I wrote a letter to Ali.
Öğretmene soru sorduk.
English: We asked the teacher a question.
Annemize hediye aldık.
English: We bought a gift for our mother.
Çocuğa kitap verdim.
English: I gave the child a book.