What is radical 8 times radical 3?

The radical here means square root. From the given,

(square root of 8) x (square root of 3)

= square root of 24

24 can be factored as 4 x 6 such that the new radical becomes,

(square root of 4) x (square root of 6)

= 2 x square root of 6

The value is,

2 x sqrt 6