Lenz’s law states that when an emf is generated by a change in magnetic flux according to Faraday’s law, the polarity of the induced emf is such, that it produces an current that’s magnetic field opposes the change which produces it.
The negative sign used in Faraday’s law of electromagnetic induction, indicates that the induced emf ( ε ) and the change in magnetic flux ( δΦB ) have opposite signs.
Where, ε = Induced emf
δΦB = change in magnetic flux
N = No of turns in coil