If the current is same in the series circuit then what does a resistor do to really if not less the flow of electrons?
"the current is same in the series circuit". This means that the current (rate of flow of charge) is the same all round the circuit. If 1.2 A leaves the battery, 1.2 A will be returning to it and there will be 1.2 A at intermediate points, outside and inside the battery. If you put more resistance in the circuit you reduce the current all round the circuit. So perhaps 0.8 A will leave the battery now, in which case 0.8 A will be returning to it and there will be 0.8 A at intermediate points.
I usually think of current as a flowing fluid and a pipe valve as a resistor. If you close the valve completely (have a pure resistor), then no flow (no current). If you completely open the valve as if it's not there, then infinite flow (infinite current). If you partially close/open the valve, there's a slight "resistance" on the flowing fluid, requiring more time for it to travel across. Although it takes more time to allow the fluid to flow through the valve, the incoming and outgoing amount of fluid is always the same --- it's just the rate of which it moves is slower.
Going through a resistor, an electron will experience thermal loss (heat) so the resistor will physically get hotter. Thinking about it in this sense, you would intuitively think "if it loses energy after entering a resistor, it'll come out with less energy and therefore less current"--- no. The electron is a lazy guy... they'll always take the path of least resistance (they don't work hard, they work smart).