One entire reading of this textbook equips you with the fundamentals of econometric modelling at the undergraduate level, to which you could begin simple empirical projects with OLS, panel data regressions, time series regressions and more.
Wooldridge goes into the details of modelling and the implications of the formulae to a deeper level than Stock&Watson, with concepts slightly above the bachelor level kept to the chapter appendixes. Many details mentioned in the book are necessary for a full-term course in econometrics, but it sheds light on the complexities of the statistics used that perhaps will not be approached unless in a grad-school class.
If you want a firm and structured understanding of fundamental econometrics, I recommend none other than Wooldridge's rendition of his most excellently elaborated field.