When it's said the c19 vaccine has a 95% efficacy, does it mean you have a 95% chance of not getting covid or not getting serious symptoms?

95 percent chance that you will not develop severe medical issues from the vaccine within a few years.

First off, the placebo group (people who did not get an active covid vaccine) had covid-19 66% less than the general population.  As such, the effectiveness that we were told did not provide real life information. 

- Part of it is that testing was predominately done on healthy 40-54 year olds. It also included only 25% minorities.

We don't know how effective the covid vaccine is in the general population.  A high level researcher said last week "it's too early to tell" which is pretty much a big punt.  The phase 3 testing was only 3 months and at the time of the statement, the vaccine has been available to the public for over 2.5 months. (we are 6 days shy of it being available in the US for 3 months and other countries a few days shy of the 3 month mark).

Also the effectiveness changes over time.  The moderna and pfizer vaccine are showing decreased antibody levels at day 59.  So they might come on stronger and putter out sooner.  The J&J vaccine continues to increase in antibodies at least until day 79.

What does the 95% effective mean.  You have a 95% less chance of getting covid, if the 99% is true. 

No.  It means that you chance of getting symptoms serious enough to be counted in the studies (which are based on the original virus, not the new variants) is 95% less than if you did not get the vaccine.  For example, if you would have had a 40% chance of symptoms serious enough to be counted in the studies, then that chance is reduced to 8% (because 95% of 40% is 32%).

Your real chance, considering new variants that weren't discovered in time to be studied, is unknown.

unrelated to pf

It means if you are exposed to a Covid infected person 100 times, 95 times you will not contract the disease.

This is why we need to get vaccines into the arms of everyone who wants one as quickly as possible.