Actually, where Brianna says that first cut is for horses is wrong. I know some people do that, but first crop is extremely weedy and tough and horses have a lot more sensitive digestive systems than say goats of cows
At my house, we usually get three, sometimes even four crops or cuts- this year we think we'll get five- but it means when it's cut. The first crop is usually early June. This one usually has the most weeds and such in it, so for my horses we'll feed half a bale of this and half a bale of the second or third crop from last year.
Hope this helps!
The meaning of the first, second or third cut hay is when the hay is cut more than once. So for an example a third cut hay is when it has been cut two other times before the third cut. Hope this helps.