Literal translation
don't force (yourself)!
Meaning
don't strain yourself
Explanation
Forces here is a verb form built on the verb forcer, to force, directly related to French, and pas carries the negation; the expression literally means don't force yourself, in the sense of don't make an effort, but it is used systematically ironically, as an antiphrasis, addressed to someone who precisely is not straining at all. Saying forces pas to a visibly inactive person thus underlines by contrast their laziness or lack of involvement, the irony lying in phrasing as a recommendation what is in fact already, and for a long time, the plain reality of their behavior. The transcribed pronunciation forcès pa shows the local phonetic adaptation of the word, built on a root largely shared with regional French, with no distinct, separately attested Provençal stock behind it. The register is familiar, cheerfully mocking, used among friends or colleagues to comment with amused irritation on someone visibly doing the least possible in a shared task.