It is represented by letter L. The coefficient of self inductance of a coil is defined as the weber turns per ampere in the coil i.e.
The unit of self induction is henry. If in the above expression I = 1A, and I Wb. Turn than L = 1 Henry.
Hence a coil will have a self inductance of one henry if a current of one ampere when flowing through it produces a flux linkage of 1 Wb, turn in it.
It can otherwise be defined as “a coil has a self inductance of one henry if a change of one ampere/sec causes an induction of one volt in it.”