The needs stack is a way of describing what a customer is trying to do when they are buying. There is always a hierarchy of needs the customer is trying to satisfy which businesses are competing to satisfy. For example, in using the Needs Stack for competitive strategy by A Smart Bear, the author talks about “buy infrastructure” vs “set up WordPress” and going up the stack to “get lucrative speaking gigs around the world”.
Buying a thing is a means to some end. If you know the target customer well, you can use this to find the right level of the needs stack to obviate competitors and better communicate value to the potential customers.