0 stripes = knows where the coffee machine is
1 stripe = knows how to order coffee
2 stripes = knows where to get papers and docs for flight
3 stripes = knows someone who gets the papers and docs
4 stripes = knows someone who can read the checklists and start engines
5 stripes or 4 stripes with a circle = knows someone who can be blamed if something goes wrong.
Sorry, couldn't resist
It all depends on the country (culture) and the company. In general, 4 stripes are for captain, 3 stripes for first officer, 2 stripes are not used everywhere, they indicate usually a F/O under training.