Simplify the following text for a Grade 4 native English-speaking person.
Original: The six letters `` A '' , `` E '' , `` I '' , `` O '' , `` U '' , `` Y '' denote vowel sounds ; the variants with a tilde are nasal vowels .
Simplified: `` A '' , `` E '' , `` I '' , `` O '' , `` U '' , `` Y '' are vowels , just like English .