What's a Tie Shear?

I have no idea what a Tie Shear is but I'll leave s link to one below. I purchased the .stl to the N scale Tie Shear on Cults which is a 3D design portal for people who want to sell their designs. I had to have this Tie Shear for my Japanese trains so I purchased then found a 3D printer online and had it printed in resin. Pics of the 3D model are below and a link to the print as well. Below are some actual pictures of the 3D print which are the best but I'll be posting better pics once I get the model in hand.

https://cults3d.com/en/3d-model/game/n-scale-tie-shear-mow