Question

what is ionisation and reduction potential

Answer 1

Ionization potential or ionization energy is the  energy an electron in an atom of element absorbs to become ionized.  The electron absorbs the energy, and is escapes the atom.  The element gets ionized to a positive charge.  It is measured in eV - electron volts or joules. 
When an ion (charge +1)  is further ionized by loss of 2nd electron, that energy required is called 2nd ionization energy/potential.


Reduction potential is the measure of the tendency of positive ions to accept electrons and get reduced.  The potential is measured in Volts or millivolts.  It is measured as the potential difference between a neutral electrode and the reference electrode in a solution.