For years I've been thinking and listening and writing and talking about the process of Shavuos.
Its date is not given in the Torah. In Parshat Emor it is not given a name, just called the holiday on the fiftieth day.
When it comes to Shavuos, though the text talks about agriculture and sacrifices, we talk about Torah.
The Aruch HaShulchan says that the sacrifices are literal and also metaphorical. The korban offered at the start of this time period, which is the source of the name we use for these forty nine days, is the Korban Omer. It was an offering of barley, which (as explained in the context of Sotah) is primarily animal food. At the end of this time, on Shavuot, an offering of loaves of bread is brought. This represents how the Torah takes us from our animal state and transforms us into people.
Rav Nebenzahl explains that Shavuot is called by this name by all of us, as opposed to other names, to stress that it's the buildup that counts - thus the day is named "Weeks."