switching off head light

on travelling on road,to get prority in going forward,just switch off & switch on head light few times .But the opposite vechicle also switch off & switch on head light ,what this signal means?

That is called flashing. It is done by pulling the headlamp stalk towards you to activate the high beams. Switching on is different and this is different. Flashing of headlights can have different meanings;

1. When you want to request the vehicle in front to let you pass, you flash the lamp and wait for him to give way.

2. When you see an opposite vehicle trying to overtake another car and tries to enter your lane(in a two lane road), you warn him to stop by flashing. 

3. In a narrow section of road where one vehicle can pass at a time, the first vehicle to flash headlight should be allowed to pass through(dont know which CMVR states this, but have observed frequently). That is what avoids getting stuck up in the middle of a narrow road.

4. When you are overtaking and in the middle of doing so, you flash and instruct the opposite vehicle to let you go through. 

this mean that ,after I  flashing the head light and to wait for the other to flash back then I  take the move forward??

No you just have to wait for the other person to give way.