than how does that comes

in physics direction of electricity is related to movement of positive charge. and because positive charge does not exists (only exists negative charge which is electron and positive charge is related to absence of negative charge aka electrons) so when electrons go from negative pole to positive, positive charge goes oppositely. thats why physicians say that electricity moves from positive to negative while electrons move from negative to positive. i am sorry if i was not clear enough. but you can watch this video