This is the 8552nd most frequent Polish word.
primera
The word "primera" is not Polish; it is Spanish and means "first" (feminine form) or refers to "premiere" depending on the context.
Here 'primer' indicates 'first' as in 'first attempt'.
To był jej primer w malarstwie.
It was her first attempt at painting.
In this sentence, 'primer' refers to a preparatory coating applied before painting.
Kupiłem nowy primer do malowania.
I bought a new primer for painting.
Here 'primer' references an introductory or basic text or instruction to be reviewed.