the SI unit for charge is the coulumb, $C$. an electron has a charge of $-1.6\times 10^{-19}C$ and a proton the same in positive phase.
$$ C= s\;A $$
current is given the symbol $I$ and is measured in amps, $A$
$1A=1 C\;s^{-1}$
$R$, this is how resistant the conductive material is to the flow of charge and is measured in ohms, Ω if a potential difference of 1V in a current of 1A then the material has a resistance of 1Ω
$$ Ω=V A^{-1} $$
$$ V=I\times R $$
potential difference is measured in volts, V
the driving force that pushes the electrons or ions around the circuit. it is the product of the resistance of the circuit and the current.
$$ J\;A^{-1}\;s^{-1} $$
all of electrochemistry is based on redox reactions and the transfer of electrons from one species to another. we can exploit this process to generate electricity via the flow of these electrons or prompt chemical reactions using our own electrons
example of an electrochemical system:
$$ \ce{Zn_{(s)} + Cu^{2+}{(aq)}-> Zn^2+{(aq)} + Cu_{(s)}} $$
this is a basic example of a redox reaction which involves the transfer to 2 electrons from the zinc to the copper ion. if we harness this flow we can generate electricity
the conductivity of the solution is given the symbol κ
$$ κ=\frac{d}{A}\times\frac{1}{R}=\frac{d}{A}\times S $$
this gives the unit for κ as $S\;m^{-1}$