Bufferbloat is temporary latency due to buffers being filled during moments that data isn't able to be sent over the line. This is often an issue for cable internet customers because of the shared nature of the cable system. It's most noticeable in online gaming, and sometimes in VoIP applications, where low latency is extremely important and a sudden 300+ms delay becomes noticeable, even if it's just for a moment. It's not so much a slowness issue as it is a latency issue.
There are a couple of different ways that you can add Codel to the traffic shaper. The best way for you might be different than someone else depending on what other traffic shaping is being done. If you're not doing anything else, then you can add Codel directly to an interface in the traffic shaper. That has worked great for me, raising my Bufferbloat score from a D to a B.
