Mistake proofing; what does it mean? where to use it? when? and how?

mistake proofing or what is called poka yoke , is a method that be used to have zero defect , by implementing of an approach to prevent the incidence of a mistake that depend on human or machine variance

Mistake proofing, or its Japanese equivalent poka-yoke (pronounced PO-ka yo-KAY), is the use of any automatic device or method that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred.

I think error-proofing is described well in below comment.
Where, when & how to use it: In Lean, Poka-Yoke (Mistake Proofing) is part of Jidoka (first time right quality).
In Jidoka highlighting problems is encouraged though tools such as Andon System (system for immediate reporting on problems to every related individual) and Visual Management, and then Root Cause of problem is identified by people as a team using techniques such as5 Why Analysis (ask why (the problem/ cause) Occurred? until answer becomes obvious).
After this analysis team is in a better position to prevent this root cause from occurring in future (usually creative ideas are required from team), this is called Poka-Yoke.
Problem may be Quality problem or any other of the seven wastes.
Jidoka is necessary for implementing JIT (Just in time), if JIT is implemented without Jidoka system will fall apart.
Moreover concept of Respect for people is also extremely important to properly implement Jidoaka in order to do Mistake-proofing.

mistake proofing :- Is preventing the error or the mistake from  occuring during the process as a prvrntive tool may be by automatic process or by the part design.

Poka yokes or mistake-proofing keep processes from producing errors. Preventing errors obviously improves quality, but it also plays a major role in improvingproductivity. With no rework, and easier production, cycle times andlead times both become much shorter. And, of course, faster production with fewer defects means lower costs.

 

Most computer manufacturers, poka yoke their cables so the plugs only fit in one way. This prevents damage to the system. Printers stop printing when the paper is out. This keeps them from spreading ink all over the internal mechanisms of the machine. A sensor in a gas nozzle knows when your tank is full. This is a poka yoke that prevents dangerous messes by shutting off the pump.Poka yokes are equally important in the office and on the shop floor.Becoming good at making poka yokes takes practice. The more you create, the easier they are to develop.

 

Mistak proofing is the way which used to prevent any wrong action it can be used any where specially at the deffect area when you want to prevent an usal mistake 

 

For example Try to put your sim card in a wrong way