This is the 3614th most frequent Arabic word.
أنهما
"أنهما" means "that they (two)."
In this sentence, "أنهما" is used as a conjunction to introduce an embedded clause, specifying that the two individuals (dual) mentioned are the subject of the verb "كانا."
قال الطالب أنهما كانا يعملان معًا.
The student said that they (dual) were working together.
Here, "أنهما" serves to introduce the belief about the action performed by the two individuals in the dual form.
أعتقد أنهما قد نجحا في المشروع.
I believe that they (dual) succeeded in the project.
In this example, "أنهما" is used to note the subject (dual) of the appearing event linked to studying.