It probably means he earned a Bronze Star Medal. The medal was awarded to the soldier in a case that included three items: A bronze Star Medal, a ribbon and maybe a metallic version of the...
A small bronze star on a Coast Guard ribbon indicates a subsequent award. YNCSOHV
Each Bronze Star represents a separate campaign (battle) they were part of. Four Bronze Stars four seperates campaigns.
No one knows for certain and no comprehensive listing exists.
10 [edit] Four-star positions