I am reading the book

Baum, C. F. (2006). An Introduction to Modern Econometrics Using Stata (Stata Press, ed.).

In Chapter 9 there is written that

Given panel data, we can define several models that arise from the most general linear representation:
Array
[...]
Assume a balanced panel in which there are T observations for each of the N individuals. Since this model contains k x N x T regression coefficients, it cannot be estimated from N x T observations.
I had two questions:

1. Why is says I have N x T observations? I should have 1 observation for each time, for each individual AND for each regressor. So I should have k x N x T observations, right?
2. Why this general model cannot be estimated?