A feed is an easy to use way of keeping up to date with lists of information on the web.
You normally subscribe to a feed using a feed reader which collects together all the feeds you subscribe to and also provides a way of unsubscribing should you get tired of a feed. Many browsers have feed readers built in, as do most email clients. In fact, a good way of thinking about feeds, is as a cross between subscribing to an email newsletter and regularly visiting website's news section.
I have been involved in the voluntary sector for some 20 years, mostly helping on the financial side. I have also written Excel programs to simplify tasks, some of which have been very complex e.g. analysis of patients in a Persistent Vegetative State, a program submitted to NHS Innovations.