The Fundamental Theorem of Algebra states that a polynomial of degree \( n \) will have exactly \( n \) roots (including multiplicities) in the complex number system.
For the polynomial \( y = 8x^5 - 2x^4 + 6 \), the highest degree term is \( 8x^5 \), indicating that this polynomial is of degree 5.
Therefore, according to the Fundamental Theorem of Algebra, this polynomial will have exactly 5 roots (counting multiplicities).
So, the correct response is "five roots."