For a short answer you could start by saying:
"By workload automation we mean software that automates the many back-office processes your business applications need to run. Workload automation goes beyond job scheduling, allowing enterprises to integrate and manage dependencies for processes that span multiple business applications and heterogeneous server platforms. Workload automation includes job scheduling which has historically been used to manage the submission of jobs at the operating system level."
Well, that’s all very tidy but what does that mean, and more importantly why did workload automation happen?