On the American side of the equation we are sending what looks like the "ready brigade" of the 82nd Airborne Division from Fort Bragg. This is a "light infantry" composition, so it is not equipped to face up to an armored division/opponent. However, it is very deployable and so off they go!
The total number of soldiers being "moved forward" to NATO countries is reported to be about 3,000. That is the equivalent of a brigade. One division would usually have three brigades.
Most Americans don't know that the United States Army is about half the size it was when I competed my military service in 1991. When I was in then West Germany in the 1980's there were over 250,000 American troops in Europe. Few remain today.
Really, what the deployment of American forces means is not so much a show of force, but a resolve to protect NATO countries, some of which were previously in the Soviet Union. Sending a message to Putin that there is "some resolve."