What do each of the three SVM classes in R represent?
Go to the kaggle site that you shared. 
Click on Data on the left. Click on datadict.txt. This is known as data dictionary, a file that help us understand the dataset.


We can see

23: outcome 
- what eventually happened to the horse? 
- possible values: 
1 = lived 
2 = died 
3 = was euthanized 


Those are the meaning of the $3$ classes. You might also like to print out hodata$outcome or do str(hodata$outcome).