Log job info is a default Switch app that issues a (warning, debug or info) message to the Switch execution log containing the value of the specified metadata field. It is intended mainly for use while testing a flow.
For example, you could issue a warning message whenever a file arrives in a particular flow element, or an info message that displays the size, the priority, the submission date, … of each job moving along the flow, ...
For further analysis of your messages, you could use a Switch app like Switch Logger or DataLogger
For a detailed explanation, check out the eLearning course (for Switch users with a subscription or an active maintenance contract).