Galvanometer A very sensitive meter used to measure tiny currents, usually 1mA or less.
A NAND gate can have two or more inputs. The o on the output means not showing that it is a Not AND gate. The output of a NAND gate is true unless all its inputs are true.
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.
An EX-NOR gate can only have two inputs. The o on the output means not showing that it is a Not EX-OR gate. The output of an EX-NOR gate is true when its inputs are the same (both true or both false).