Plz explain the conventional flow of electric current and what happens in reality???

The conventional direction of electric current is from +ve terminal to the -ve terminal, through the outer circuit.This is bcoz, in olden times it was believed that it is the positive charges which flow in a circuit [electrons were not discovered by that time]. But the `actual flow` of electrons is from -ve terminal to the +ve terminal. The conventional direction of current (i.e from +ve to -ve) is usually marked in circuit diagrams.

Thanks Smrithi!