Near as I can figure, you're looking at pilot air jet, main air jet, idle air jet, and some other air jet openings. They work with the jets in the float bowl. No plugs or obstructions allowed. Don't jam wires in them to clean them out. Use compressed air with rubber tipped air blower. Soaking in carb cleaner can be used if they are crudded up. But this means disassembling the carbs.

 

Ya they are just the carbs jets is all and I agree gpfan1 with his way of cleaning them. compress air becomes your friend when cleaning and carb cleaner.