The Jump command allows some units to traverse terrain by temporarily entering air-space. Most of Jumpbots, Dirtbags, Recon Commander and Detriment are able to jump (also, Lobster's attack has mechanics which work in a similar way). Default key is J.
Jump provides big tactical advantage for traversing terrain, retreating, attacking from unexpected angles and more. Jugglenaut can use its jump to directly inflict damage. While jumping, units have several vulnerabilities, such as easily read landing location and inability to change course.