Can anyone explain what is meant by electro magnetic induction

Dear student,
Induction means influence without contact.

If we move a magnet to and fro in the vicinity of a conductor (for example a coil connected with a galvanometer) we find electricity is generated in the coil without contact with the magnet. Thus it is called electromagnetic induction. 

A change in magnetic flux (or number of lines of force = φ ) through a metal surface or a circuit induces an emf in it and this phenomenon is called electromagnetic induction. Faradays law of electromagnetic induction states that the magnitude of emf (e) induced is equal to the rate of change of flux through the area of the circuit.

e = -dφ/dt

The polarity of the induced emf is explained by the Lenz’s law. The law states that the emf induced is such that it opposes the change that has induced it.

Regards.