About Punctuation...
Why are there question marks both at the beginning and end of the sentence in Spanish?
Is there an explanation of this?

2 Answers
In Spanish we don't have the particles "do/does", nor is necessary to invert any part of the sentence to indicate a question.
So, when reading, without the opening question mark you woudn't know if a sentence is a question until the very end of it.
Hi! es para indicar dónde comienza la pregunta y dónde termina.