This is the 3356th most frequent Arabic word.
طفلا
"طفلا" means "a child" or "boy" in English.
In this sentence, 'طفلاً' (a child) is used as the predicate to describe the subject 'He' in his condition during his school time.
كان طفلاً سعيداً في مدرسته.
He was a happy child at his school.
Here, 'طفلاً' is used as the direct object of the verb 'رأيت' (saw) to indicate the entity being observed.
رأيت طفلاً يلعب في الحديقة.
I saw a child playing in the garden.
In this context, 'طفلاً' serves as a desired state or identity in the wish expressed by the subject.