I was also unclear about whether they mean "How many workers in the US could work from home", or whether "How many job categories can work from home". But they

I was also unclear about whether they mean "How many workers in the US could work from home", or whether "How many job categories can work from home". But they state "To answer these questions, we classify the feasibility of working at home for all occupations and merge this classi cation with occupational employment counts for the United States." So it looks like they're counting number of workers.