suppose that two people are fighting and one of them gets knocked down and the opponent yells "Fe pa li" what would that mean? would it mean "get back at him/her " or "your going to get it"

Fè pa li → give him/her a break, forgive him/her, go easy on him/her, show some mercy, etc...

using appropriate pronouns:
Fè pa m → forgive me, ...
Fè pa n → forgive us, ...
Fè pa yo → show mercy towards them, ...

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