Like many things, "paper" is sometimes countable and sometimes uncountable.
Normally it's uncountable, but often "a paper" can mean a written composition, an official document or a newspaper. When used in those senses, it's countable.
In your sentence, I'd guess the "papers" are either written reports or newspapers, but without some more information I can't say for sure.
Here's another example of a normally uncountable noun used in a countable sense: "Tea with two sugars, please." Here, "two sugars" means two lumps or two spoonfuls of sugar.
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