Circuit 1... Resistors and Diodes.
Circuit 2... Resistors, Capacitor and Zener (or Avalanche) Diode.
Circuit 3... Resistor.
Circuit 4... Triac, Resistor, Capacitor and Thermistor.
Google each of above names for descriptions of their function.
ZigZag lines/ wave lines are resistors, Triangle with a flat line at the end is a Diode, Triangle with a bent line at the end is a Zener Diode(conducts only above/more than a certain volage, eg BZX 12V5 is 12.5 Volts.........BZX 10V0 is 10Volts etc) Triangle with a flat line across the end and arrows pointing outwards is an LED (Light Emitting Diode- it emits light/lights up) two Horizontal straight lines separated by a space is a Non-Polarised capacitor, if it has one of these lines darker than the other one then this is the circuit symbol for a Polarised Capacitor which must be connected in the correct direction/orientation, the cathode side has a white band/ minus printed on it and is the negative side, it is the black side of the symbol, with the white side being the anode.... The optocoupler part is one component sealed inside one 4 pin package/Integrated circuit acting like an electronic switch for the +volts giving a TTL (Transistor-Transistor Logic) output (switching 5 volts on and off) and basically has a type of LED device inside alongside an optically initiated transistor device that conducts when exposed to a certain wavelength of light emitted by the LED device sealed in beside it... inside the oval shaped circle(the long circle) is a rectifier diode along with a current limiting resistor, the same as the two outside of the circle, try to picture the 2 diodes side by side pointing in different directions.....helps prevent damage to opto isolator if DC connections get reversed.... on the AC diagram, the resistors on the Line and Neutral (Live and Neutral/ Ground) input terminals/connections are current Limiting.... Diagram "Electric2"- the resistor in the top diagram is a Pull Up resistor (label as RP) the second drawing has a Diac which operates to conduct over a certain voltage a bit like a zener diode but in two directions instead of one..... the middle red circle on the second diagram in "electric2" is an RC Filter (resistor Capacitor filter) the last symbol is a preset potentiometer (variable resistor) which is turned/changed with a screwdriver... the bottom diagram shows a relay switch being operated by the TTL output from the optocoupler causing the transistor to conduct by saturating the Base, connecting the relay to ground like a switch and allowing current to flow and energise the magnet, which operates the mechanical switch.... TTL to Base Relay to Collector Emitter to Ground/Neutral, Relay connects to ground via the transistor collector/emitter... hope this helps a bit... had to re-type this just there as my browser keeps kicking me off so I have to log back in every 5 minutes...