I think that means something like all the individual values in the @ar1 list of values are less than at least one of the individual values in @ar2.
> my @a = <1 2 3 4>;
[1 2 3 4]
> my @b = <2 3>;
[2 3]
> say so all(@a) < any(@b);
False
> say so all(@b) < any(@a);
True