Following are some settings which are used in helicopter.

1. Throttle curve
2. Pitch curve
3. Ideal up
4. Throttle hold
5. Various kind of Swashplate mixing like 90 degree ccpm, 120 degree ccpm etc.

I want to know what are the functions of these settings and how they work.

1 on a helicopter u need pretty high head speed all the time do the rotorblades are (the wings), u set the curve to desired head speed , all depends on witch helicopter and powersupply

2  the angle of the blades is changing with the curve u set , how much lift u want on the heli  and where u want it at different stick positions

3  normally u need a setting for taking of and sport flying where u can get motor to idle or stop for start and landing and minimum 1 for 3d flight where u have full gas on negative and positive pitch

4 throttle hold is a switch where u kill the motor or idle

5 90 degree is the servos in 90 degree to each other on the swash plate and 120 is 120 degrees to each other
u have to make sure your radio is supporting desired ccpm mixing