neden söylüyorsunuz - why do you say?
olabilir - there may be
Çok sayıda sebebi - a large number of reasons/many reasons
I would probably find an explanation in a grammar book, but maybe there is a simple explanation.
|Question:||Why is 'diye' used in this sentence?|
|Lesson:||Turkish LingQ - Who is she?, Part 6|