Inject job is a Switch default app that injects a job into the flow when triggered by an incoming job or by various time-based events. The injected job can be selected dynamically from a repository of jobs, it can be a fixed job, or it can be the incoming job itself.
The properties for each outgoing connection specify what needs to happen for that connection (independently of other connections). For example, to inject a job from a repository based on the metadata of some incoming job while keeping the original job around, setup one connection to receive the incoming job, and a second connection to receive the job from the repository.
For more information, check out the eLearning (only for Switch users with a subscription or active maintenance contract).