Let's create a variable with a series of data points:
HHsize<-c(2,3,2,1,4,5,1,1,2,5,1,2,2,6,1,2,2,4)
We've created a vector to hold these data points. You can imagine, as we discussed, that each data point is in a box, and the vector is a stack of boxes. It doesn't matter if the boxes are stacked vertically or horizontally.
We can refer to a specific box by using the square brackets, [ ]
HHsize[3]
This refers to the third data point in the vector, which in this case, has a value of 2.