What is gfci? Where it can be capable for using and what is the advantages and this advantages please send to answer my mail
Thank you

Suggest you Google "GFCI circuit " for very extensive info. Basically they are safety devices used in areas where water may be encountered.

Basically it trips when the hot or neutral draw more than the other, which would mean an unintended path such as yourself. If the hot goes through you to ground, the hot is drawing more, and it trips.
It is for safety, Particularly Outdoors and near water.
I would Google to get more info as mentioned.