First off, Dest is a lable is a label which has been placed in the assembly source code at the address of the procedure to be called. (think of it as the name of an address of a function)
1) the address of the instruction immediately after the call instruction (AKA the return address) is pushed on to the stack.
2) The Dest (it's an address remember) is assigned to the %rip register.
This means that when the called function begins execution, the return address to the calling function is the last thing that's been pushed onto the stack.