Why Are Galilean Transformations Important in Understanding Relative Motion?

[ysk1]

I understand the concept of relative motion, but I don't know why I can't understand what Galilean Transformations are. Could anyone please explain it?
Thank you.

 

[Doc Al]

It's just a way of translating measurements (e.g., of coordinates, distances, speeds) between different moving frames. Try this: http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/ltrans.html"