I sell enterprise software that helps companies automate their supply chain or trading partner communities (customers and suppliers). The sales executive [aka Account Executive (AE)] is resonsible for developing the business (i.e. cold calls). Your job is to be the technical expert or software expert or industry expert or all three.
You will help uncover opportunities once the AE secures meetings with prospects. What are their business needs? What are their pain points? Once you find these out, you match one of the products you sell that will help solve these business pains. You may demonstrate the product's capabilities customized to their business, respond to Request For Proposals, answer technical questions, etc.
Your job is to tailor your message based on your audience. You need to be comfortable with public speaking, have good writing skills, and a capacity to take complex concepts and communicate them in ways that others can understand. Ultimately this results in sales if your effective.
A software sales engineer is great way to earn a living. You don't have as much upside potential as an AE but you also don't have as much risk. If the AE misses a few quarters of quota, he's out on his ear. As long as you are doing a good job, however, it is less likely that you will be laid off. Of course, if your company is missing sales quarter after quarter everyone needs to worry.
I'm making more doing this than I would have ever made as a civil/environmental engineer. It also requires some travel depending on the company or territory. It's not that easiest thing to break into though if you have no software experience but it can be done. I did it. How I did it is another thread altogether.