This is the 812th most frequent Turkish word.
insanı
The Turkish word "insanı" means "the person" or "the human" (in the accusative or possessive form, depending on context).
The word "insanı" here is used in its accusative form, referring to "a person" as the direct object of the verb "etkiler" (to affect).
Doğa bazen insanı derinden etkiler.
Nature sometimes deeply affects a person.
In this sentence, "insanı" is again accusative, referring to "a person," directly tied to the action of the verb "teşvik ediyor" (encourages).
Bu kitap insanı düşünmeye teşvik ediyor.
This book encourages a person to think.
The term "insanı" is in the accusative case, identifying "a person" as the one being emotionally affected.