Its a pretty lengthy subject, you should defo read up on it, but basically you save money by reducing inventory waiting to be processed/shipped, eliminate waste (quality problems, time stock is sat waiting, over production) and get an overall more productive manufacturing system.
Its how Toyota beat US car makers back in the day, and has been applied to many other sectors, heavily influencing software development (e.g. moving from big batch development deployed once every 6 months, to single piece flow deployed multiple times a day)
"Making your process as flimsy and unresilliant as possible"
It does quite the opposite, it enables and encourages workers to make processes less flimsy and more resilient..