In Danish you don't. Both usually translate as "Jeg spiser". There is not an actual progressive tense in Danish, but there are special constructions you can use if you want to emphasise that something is currently happening, for example "Jeg sidder og spiser" - "I am eating (right now)."
Han læser aviser = He reads/is reading newspapers.
Han læser aviserne = He reads/is reading the newspapers.
Danish doesn't distinguish between "does/is doing" like English does, so both reads and is reading are accepted in these types of exercises. You added in an extra "the", though: aviser is an indefinite noun, which means it just means "newspapers" without the the.