I worked at a company owned company I wish I still worked for them! I am sure that all companies are different, as my experience is completely different than the above posters. So, understand the following information is just about my experience.
What happened with my company was it was completely owned by those working for them. The company founders wanted to make sure that it continued after them. Employees must work a certain number of hours (I think it equaled 8 or 9 months full time hours for the year) to be part of it.
There were two times during the year that they admitted members and after which ever date came first after you qualified, they enrolled you in the stock sharing program. They had a formula for how much stock dividends you would receive depending on how many hours you worked for the year and how long you had worked.
After five years you were fully vested (it was seven when I worked for them). If you left the company before that time you would receive a prorated amount of stock. You could not take the money, it stayed with the company. When you retire, you can request the stock and receive it in three installments- I cannot remember how long the intervals were/are.
One thing that was good (at the time, but bad too...) was in 1993 after I left the company I received part of the stock in cash. I really was broke at the time and for some reason stock before a certain date was available. BUT I lost the value of that money growing, plus I was suppose to pay penalties and tax but never did. Lucky for me the IRS never audited me or I would have been in trouble! I still have money awaiting me when I retire.
I love my old company and if I could find the right position (my old traveling division is gone!) I might go back.
I would think you need to research this company, find out what it means. All companies have public information about stocks, I believe. Not sure if you can find that, maybe you have to ask the company for a copy of it. But they should be willing to share it with you. This might be better than just asking them what it means.
Again, this is about my old company only.
Good luck with this. It can be a great benefit.