Questions & Answers about Ben çantayı yanına koyuyorum.
In Turkish, the verb ending already shows the subject. Koyuyorum means I am putting, so ben is not required.
The sentence could simply be Çantayı yanına koyuyorum.
Adding ben usually gives a little more emphasis, contrast, or clarity, as in I’m the one putting the bag next to him/her/you.
Because it is the direct object and it is specific/definite.
Turkish often marks a specific direct object with the accusative ending -(y)ı / -(y)i / -(y)u / -(y)ü. Here:
çanta + -yı → çantayı
The y is a buffer consonant added because çanta ends in a vowel.
So çantayı means the bag or that specific bag as the thing being put somewhere.
Yanına literally means to his/her/its side or to your side, depending on context. In natural English, it usually means next to him/her/it/you.
It comes from yan, which means side. Turkish often uses words like side, inside, top, front, and so on with possessive and case endings to express meanings that English often expresses with prepositions.
So instead of one simple word for next to, Turkish often builds it this way.