This one is basically a google challenge. 1. The text for the hint is "This x86 instruction is an alias for pop eip/rip." 2. Take keywords "x86" "pop eip" and enter them into google. 3. Second result has the following;
%esp points to the last thing pushed on the stack.
%eip points to the next thing to execute.
call <addr> pushes the current value of %eip and changes %eip to <addr>.
ret pops the next value off the stack into %eip.
Arguments are pushed onto the stack before a function call.