The word very is an intensifier, suggesting a high degree of a quality. Something great is very good.
This word adds intensity to statements and means something close to really or extremely. If you are tired, you might have some coffee. If you are very tired, you might need a nap. An 80 degree day is hot, but a 90 degree day is very hot. This word also means exact, as in "On this very day, I was born" or "That's the very book you were talking about."