V1[]
RIGHT$ is not a function in SmileBasic V1.
V2[]
RIGHT$(A$,N) is a function which takes one string parameter, and one numerical parameter which gets rounded down to the nearest integer. If the number is negative, the function generates an Out of range (RIGHT$) error. Otherwise, the result of the function is the last N characters of A$. (If N is zero, the result is the empty string, and if N greater than or equal to the length of A$, the result of the function is the same as A$.)
V3[]
Indications are, RIGHT$ in SmileBasic V3 is identical to that in V2.