candlestick color shows real buy and real sell

student question

———————

hello sir , thanks for your answer

I have a very basic question….
From 2 years i am connected to you and your videos, you always say
that trade only if the price close upper side or down side of the previous candle.
What is the psychology and the basic about this, i have not understood this
Please explain in details
Thanks
———————
video here