what does it mean when a start up is described as Series ABCetc. ?

[raw thunder]

What implications does it have for potential candidates that we need to be aware of?

[marsh plinth]

Good read on this: https://www.investopedia.com/articles/personal-finance/102015/series-b-c-funding-what-it-all-means-and-how-it-works.asp
To oversimplify, earlier stage startups are higher risk/higher reward for candidates.

[raw thunder]

Thanks!