You get 60 or 90 days of notice - depends on what state you live in. Notice period can be working or non-working - the default is non-working but there are occasional exceptions. during this period you are still an employee.
Severance starts after the notice period. It is 2 weeks of severance for every completed year of service, with a minimum of 8 weeks. If you have worked any amount of time up to 4 years, you get 8 weeks. after that add two weeks for every year completed... 5 years, 10 weeks, 6 years 12 weeks etc.
So 5 years of completed service: 60 days notice (90 if you live in NY) and then 10 weeks of severance.