Now if you can do the same thing for what your input operator for BunchOfCards is supposed to do, then the next step of writing the code will be a lot easier. I have given a bunch of hints above about how in English it should work. The key is to not take them literally but to try to understand the point behind them. You won't understand all of it if you are just a beginner, but you should get enough information to write in English what it is your function should do.
Given an output stream and a vector of Length objects, this function will output all the objects in that vector. To do that, it loops through each Length object one at a time and does the following: Ouput the feet property, then output the inches property. When all objects have been output (which is determined by keeping a counter that reaches the size of the vector), then return the output stream.