services – What is concretely included in the term “architecture”

I have built two mobile phone applications, a website both consuming the same deployed backend which communicates with four external services AWS S3, a bank, a payment module, and a POS.

Googling “software architecture” I found this

Software architecture refers to the fundamental structures of a
software system and the discipline of creating such structures and
systems

If we can conclude that all of what I mentioned is included in the software system. I would consider fundamental structures be communication and run-time and disciplines to be the methodology?

I suspect that extending my googling might send me down a rabbit hole. Could anyone give a practical/concrete example of what is relevant when discussing software architecture?