What does it mean to have a blue collar job?

Blue collar jobs are usually those that are more "hands-on" or active (i.e. police officer or construction worker) as opposed to white collar jobs which are usually considered office/desk or professional jobs (i.e. accountant, doctor, etc.)

Blue-collar job usually mean those jobs that are more physical in nature while white-collar jobs are associated with computer work, finances - stuff that is more intangible. White-collar jobs involve people wearing a suit. Blue-collar doesn't due to the natue of the job. Hope this explains stuff.

Blue collar jobs consist of manual labor and workers are usually paid hourly wages. Pretty common.