I have a small scale 10-acre sheep farm and this is how I make hay as a backup food supply for the sheep.
What is hay? Hay is essentially just dried grass that farmers can store up and feed animals in winter or during a drought when no grass is growing.
First you cut the grass using a special sickle bar mower that works with a scissor action, cutting off plant material at the base. Since it does not shred the cut material into small pieces, but leaves it whole, it can be easily raked and baled for hay. Once cut, the grass must dry out for a couple days. After drying, it needs to be raked into a windrow to make it easy for the baler to pick it up.
Theres a video of the mini hay baler in operation here:
https://sheepdogfarm.com/f/making-our-own-hay