I think you are right in both respects.  This mutation is one of the most common ones found in 21-hydroxylase CAH and it is found with high frequency among those of Ashkenazi Jewish decent. 

 

I’m not sure if this is what you are asking by, "What is it?"  BUT, what V281L is is a type of mutation known as a "point mutation."  With a point mutation, a single piece of DNA on the gene is produced in error, leading to loss of function of that gene.

 

In this case, "exon 7," refers to the place on the 21-oh gene, where this error occurred.  "281" refers to the particular position on exon 7; "V" stands for the name of the chemical that should have been produced; and "L" stands for the name of the chemical that was erroneously produced, instead.