Jobs: It is a way to encapsulate/fine-grain every little computation the game engine needs to do (usually called jobs/tasks) so these can be freely distributed to any available CPU core (it just picks the next queued-job once it finishes the current one). So if your console and/or computer receives more cores overnight then not much work is needed (if at all) to put them into use.
More and more game engines have switched over to this method over the last few years as a great means to harness multi-core CPU's and to be able to easily scale as more advanced CPU's with more cores are introduced. This was ecspecially useful on the PS3 CELL as it had one master-core and six slave-cores (SPU's).
Naughty Dog has taken it a step further with their PS4 engine starting with TLOU: Remastered. Usually you have one CPU core dedicated to 'orchestrating'/manage the whole Jobs system but ND's PS4 engine is fully parallelized in that it doesn't need this at all. All of the six cores are happily computing jobs (and with this new SDK they have seven). This thanks to the magic fairy dust of 'fibers' (jobs-within-jobs) that can cooperatively yield to each other and resume their work where they left of later on combined with core-locked worker threads... Basically: Their engine is more or less perfectly scalable. Enabling and fully utilizing a 7th core (or in theory: a hundred more cores) probably took them 30mins of coding.
They have a really cool technical talk here (one hour long):
http://www.gdcvault.com/play/1022186/Parallelizing-the-Naughty-Dog-Engine