There are different Usages of the letter N.
1. the fourteenth letter of the English alphabet
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
This letter denotes the next after M in a set of items, categories, sizes, etc. e.g. It also denotes the fourteenth of fourteen or more hypothetical people or things. Besides, N letter of English Alphabet is used in Norway as International Vehicle Registration.
In Chemistry N = Nitrogen the seventh element of the periodic table, n-hexane means normal hexane with straight chain structures. n = nano where it represents the union of measurement as 1nm = 10-9 m. N = Newton is the SI unit of Force where 1N is equivalent to the force required to produce an acceleration of 1m/s2 when applied upon 1kg of mass.
The most Common Noun which is used to learn this letter at the Nursery level is Nest; N for Nest.