1099-misc

My son received a 1099-Misc.  Box 14 was checked.  This was from a settlement from a summer job employer for reimbursement of medical bills for getting hurt on the job.  It was over just $2,000.00. How much of this is consisted taxable income when it is a reimbursement for medical bills from the prior year?  And why is it being considered a Business income?  He is not self-employed. 

 

Also, is there an amount of a 1099-MISC you don't have to report?  My daughter-in-law received one for $3.25.