By "englishify" it, I assume you mean explain what the parts do:
1) (A1:A65535<>"") creates an array of FALSE/TRUE depending on whether
the cells are blank or not, respectively.
2) 1/{TRUE,TRUE,FALSE,TRUE,...} coerces the array to 1/0 (for
TRUE/FALSE) and divides 1 by the coerced array to produce
{1,1,#DIV/0,1...}
3) LOOKUP(2,{1,1,#DIV/0,1...},A1:A65535) looks through the array for the
value 2, which obviously doesn't exist, so it finds the last value *less
than or equal to* 2 (i.e., the last 1), and returns the value in
A1:A65535 corresponding to the index of that last 1.