Whatever calculation has been done within primary curly braces, all of those are only for internal use, which means, within the function. If you want the internal value as output, then you must specify that object into the return statement. For example, if you want the mean of the input vector as output from the function, then you can simply change the return statement as follows:

    fsdByMean <- function(vectorInput){
     average <- mean(vectorInput)
     std <- sd(vectorInput)
     stdByMean <- std/average
     return(average)
    }

    > fsdByMean(vectorInput = V1)
    [1] 5.4

The name of the function and other internal calculation remains the same, but the output will be different just because of the return statement.