Voltmeter Measures voltage. The proper name for voltage is potential difference but voltage is more widely used.
An EX-OR gate can only have two inputs. The output of an EX-OR gate is true when its inputs are different (one true, one false).
Transistor PNP A transistor amplifies current and can be used with other components to make an amplifier or switching circuit. This symbol is for a bipolar junction transistor (BJT), the type you are most likely to use at first.
Microphone A transducer which converts sound to electrical energy.