This line of code doesn't make sense to me, can someone clarify it in vhdl language?

Question

Can you tell me why line 2, is: i * 8? I got this code from a book.

MOV X9,XZR // i = 0
loop1: LSL X10,X9,#3 // X10 = i * 8
ADD X11,X0,X10 // X11 = address of