[Ballu Miaa]

Well you are taking it in a wrong way. You have to define a variable and get the player's armour and add 5 to do that, like this.

pawn Код:

new Float:Armour;//define a floating variable with a name Armour.
GetPlayerArmour(playerid,Armour);//Store the value of player's armour in this variable using GetPlayerArmour function.
SetPlayerArmour(playerid,Armour + 5);// You need to add current Armour + 5 to do your task in SetPlayerArmour function.