A network is often described with an edge and a core, and there can be several types of "edges".
For a company like google, you would most likely have an edge towards your servers as well as an edge towards your peering partners. The peering edge is therefore the part of the network that is used to connect to BGP peering partners.
A worthy note to add to this is that the market for credit card payment in, at least Denmark, is almost monopolized through nordic payment provider NETS (http://nets.eu). Their prices are steep and iZettle was for many a much cheaper and easier alternative.
For a company like google, you would most likely have an edge towards your servers as well as an edge towards your peering partners. The peering edge is therefore the part of the network that is used to connect to BGP peering partners.