This looks to me like a ligature – I’ve seen it come up in pronunciation sections before, although print texts may vary in exactly how it looks.  I’ve seen ligatures shown before as a line connecting two letters, or as the two letters pushed together so the lines are touching (as in “Cœur”).  In pronunciation, a ligature indicates that the two letters make one combined sound.

Ligatures are covered in UEB 4.3: the ligature indicator (dots 45, 235) is brailled in between the two letters ligatured in print.