In the first block, the createAdders() return an array of functions, and every function (created in the inner for loop of the createAdders() function body) sums the parameter n (the 7 value) with the variable i created in the loop, wich, at the end of the loop, has the value of 4 (that explains the 11).
When you made the invocation adders[1](7) the function stored in the array fns at position 1 is returned, then you invoke the function with the parameter n = 7, then the function proceeds to sum this parameter with the i variable of the createAdders function (which value is 4 at the moment invoke adders[1](7))
