This is a four step problem solving methodology.
The full form of PDCA is
PLAN-Recognize the opportunity and plan the change
DO- Taste the change
CHECK- review the tests, analyze the results and identify learnings
ADJUST/ACT- Take action based on what you learned in the check step, if the change was successful, incorporate the learnings from the test
PDCA is an iterative four step management method used in business for the control and continuous improve of processes and products.