Earlier quoted context omitted.
They are the technical person on the sales team. They do demo's, field technical questions, might do a POC with a potential customer, so on. They also get a commission but they traditionally have a standard salary as well instead of the sales rep where their salary might be 60% or more commission only.
So.. not an engineer.
Some places call them Solution Architects too which IMO is a better name as they work with customers to help them see how their company solutions can be integrated and made useful.