What does it mean when someone says you may be able to get grandfathered into a job?

I think it means that if you were working for a company and doing a job lower position job, if your boss likes your work and you apply for a higher position job you may get the job because you were already there. Grandfathered in means you were doing something or you held a position before anyone else before requirements (usually a degree of some sort) were required.
Without the usual training/education cause you have been employed in the field for a long enough time.
To exempt (one involved in an activity or business) from new regulations
It means someone can get the job by virtue of just being there the longest, despite qualification.
Someone in your family had it so you will get special treatment and access.
the rule applys to the employee that started after a certain date. the other employees that were there before that date the rule does not apply to.


Answer:
'Grandfathering' usually means the rules are being changed but people who are already involved in the activity will not be affected by the rules change.

For instance, if there's, say, a new law prohibiting the sale or use of cars with mileage below 15 miles per hour, but people who already owned those types of cars before the law went into effect are allowed to still use them, they are said to be 'grandfathered in.'

So maybe in the job context it means the rules are being changed, or there are new requirements for a job opening, but some people are not subject to those requirements because they have already been employed there. Something like that.
This term is often used (Properly or not, I don't know) in cases of mergers, where the person who keeps their position in the new company, or rises up a level due to the consolidation, is said to have been 'grandfathered.' As I say, I don't know if this is proper usage, but the bank I worked for for 15 years went through three mergers in that time (I left right before the 4th), and people used this term a lot.