Simplify the following text for a Grade 13 native English-speaking person.
Original: A digraph , bigraph , or digram ( from the , dÃ s , `` double '' and Î Ï Î Ï Ï , grÃ phÅ , `` write '' ) is a one of the characters used to write one phoneme ( distinct sound ) or a sequence of phonemes that does not correspond to the normal numbers of the two characters in combination .
Simplified: A digraph or digram ( from the dÃ s `` double '' and Î Ï Î Ï Ï grÃ phÅ `` write '' ) is a pair of characters used to write one phoneme ( distinct sound ) , or else a sequence of phonemes that does not correspond to the normal values of the two characters combined .