فَأَسْنَدَ رُكْبَتَيْهِ إِلَى رُكْبَتَيْهِ describes the visitor positioning his knees next to the Prophet’s ﷺ knees. كَفَّيْهِ is a dual form meaning “his two palms.” Regarding the hands on the thighs, the pronoun can be understood in two ways: his own thighs or the Prophet’s ﷺ thighs.
The educational point is focused attention and appropriate manners. The exact physical posture is not a mandatory technique for every teacher and every setting. Learners should listen attentively and ask clear, respectful questions.