In short, Conway's Law says any organisation that designs a system will come up with a system design that copies the organisational communication structures.
Over the years, many many people paraphrased Conway's Law in many different ways.
Every paraphrase brings new insights and non-negligible consequences. Sometimes they give the impression they contradict each other. However, in the end, they all come to the same conclusion. The organisation and the system keep each other in balance. Modifying the organisation will have an impact on the system. Modifying the system will have consequences for the organisation. Not considering that will cause friction in the organisation or the system. That may have dramatic consequences from a design point of view, but even more so from a testability and quality perspective. It will slow down teams, reduce feedback and consequently drive down quality.
To be competitive as an organisation in the market, and to effectively design the right thing our customers expect us to deliver, we'd better understand and take advantage of this.