# Number of observations in plm package, n, T, N

I am new to R. I am using the plm package to run pooled OLS and Fixed Effect. My data set has 130 countries over 33 years with lots of missing values. My model has 9 independent variables. When I run my models I get the following:

Unbalanced Panel: n=34, T=1-6, N=61


Can any body explain this? Does it mean that 61 countries have observations for all 33 years across the 9 independent variables?

I saw the same question asked here: Interpreting plm output in R - number of observations used with very unbalanced panel