Language of software engineers and skills of scrum-masters? All software developers speak the same language and that is pseudo-code :) However, there are still communication issues among software engineers specifically with other teams. That's where the role of great scrum-masters fits in. That great scrum-master does not necessarily need to be technical but he/she needs to have the skills of hearing roadblocks that engineers communicate in their technical language. I said "hearing" and hearing is not the same as listening. Listening is just a pre-requisite for hearing. Once you hear it, now you need to know how to action it and mobilize the right people. Coaching comes along with all of this, but that is a separate topic because it is also a responsibility of the tech manager. These skills separate great scrum-masters from others.
P.S. Disclaimer: On any given day, I wear a hat of a solutions architect, engineer, scrum-master and tech manager.