Shavuot is a Jewish holiday that occurs on the sixth day of the Hebrew month of Sivan (late May or early June). Shavuot commemorates the anniversary of the day God gave the Torah to the entire Israelite nation assembled at Mount Sinai, although the association between the giving of the Torah (Matan Torah) and Shavuot is not explicit in the Biblical text. The holiday is one of the Shalosh Regalim, the three Biblical pilgrimage festivals. It marks the conclusion of the Counting of the Omer.
The date of Shavuot is directly linked to that of Passover. The Torah mandates the seven-week Counting of the Omer, beginning on the second day of Passover and immediately followed by Shavuot. This counting of days and weeks is understood to express anticipation and desire for the Giving of the Torah. On Passover, the Jewish people were freed from their enslavement to Pharaoh; on Shavuot they were given the Torah and became a nation committed to serving God.
When the people of Israel received the Torah at Mount Sinai, it included special instructions on how to slaughter and prepare the meat for eating. Until then, the children of Israel did not follow these laws, and therefore, all their meat - together with the cooking pots - became from the moment the Torah was received non-kosher. Their only option was to eat dairy products that did not require special training.
Why did not the Israelites slaughter new animals, prepare the pots with boiling water and cook fresh meat? The answer is that the revelation at Mount Sinai applies on Shabbat, when one does not slaughter or cook.
It is amazing to see that that day at Mount Sinai was the first time the Israelites ate dairy foods. There is a general prohibition of "eating an organ from the living" (part of an animal that did not die), which apparently also includes milk, a product derived from a living animal. The prohibition of a limb from the animal is from the seven commandments of the sons of Noah, which the children of Israel kept even before the revelation at Sinai (and which applies to all people since the days of Noah).
However, upon receiving the Torah that described the Land of Israel as "a land flowing with milk and honey" (Exodus 3:17) [according to the simple interpretation that milk is milk from animals (see Mechilta 13:13, interpretation of another) Dairy products - in other words, on the same day their meat was forbidden, the milk was allowed, and they ate dairy foods on that first Shavuot, and we also eat it today
A picture I took from my workplace