[Burridge]

All this is, is because new float: isn't a capital F. It should be new Float:

pawn Код:

#include <a_samp>
#define COLOR_RED 0xFF0000FF
public OnPlayerUpdate(playerid){
    new Float:Phealth;
    GetPlayerHealth(playerid, Phealth);
    if(Phealth < 20){
        ApplyAnimation(playerid,"CRACK","crckidle1",4.1,1, 0,0,0,1);
        SendClientMessage(playerid, COLOR_RED, "You are dieing, You need a medic Please wait for a medic");
    }
}

Also, wouldn't it be better to use a timer, instead of OnPlayerUpdate for this? I mean the amount of times it gets called, it would cause lag if you get a lot of players.

Stigg: No. GetPlayerHealth has 2 parameters. https://sampwiki.blast.hk/wiki/GetPlayerHealth