In this one, desks are arranged the way that the students are in small table groups while they all face the chalk/white board. This encourages the interaction within students' table group. They can hear each other and almost everybody can see each other, too.
If the teacher is teaching by the white board this seating arrangement allows interaction between the teacher and the students as well. The teacher is able to see everyone and monitor what is going on on students' desks.
For whole-class discussion this seating arrangement does not work since some students are placed behind somebody's back.