[Threshold]

pawn Код:

new Float:PrisonCells[6][3] =
{
    {146.641326, 1086.450805, 523.917419},  // Cell ID 0
    {143.410385, 1086.557373, 523.917419},  // Cell ID 1
    {140.075027, 1086.834594, 523.917419},  // Cell ID 2
    {125.594047, 1086.595458, 523.917419},  // Cell ID 3
    {122.502304, 1086.180175, 523.911437},  // Cell ID 4
    {119.788101, 1086.267700, 523.911437}   // Cell ID 5
};

new id = random(sizeof(PrisonCells));
SetPlayerPos(playerid, PrisonCells[id][0], PrisonCells[id][1],PrisonCells[id][2]);

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This part was wrong:

pawn Код:

new Float:PrisonCells[][0] =

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I suggest you read a bit more about 'arrays' and how they're structured.
https://sampforum.blast.hk/showthread.php?tid=318212