Solved Please help me complete my skript.

[KIMHYOCHAN]

on inventory close:
if inventory name of current inventory of player contains "PackageSetting":
set {_inv} to uncolored inventory name of current inventory of player
replace "PackageSetting" with "" in {_inv}
clear {package.set.%{_inv}%::*}
loop 54 times:
add 1 to {_player}
add slot {_player}-1 of player's current inventory to {package.set.%{_inv}%::*}

That phrase doesn't apply. Developers who know this, please comment!
My skript version is 2.5.3.

 

[BanditEagle]

why are you trying to alter the inventory of a player after they have closed it? Did you mean to use "on inventory open:"?
also, you didn't set the variable {_player} to anything beforehand, so just before the loop it should be like this:

set {_number} to 1
loop 54 times:
    set slot {_player} of player's current inventory to {package.set.%{_inv}%::*}
    add 1 to {_player}

so, your final code should look something like this:

on inventory open:
    if inventory name of current inventory of player contains "PackageSetting":
        set {_inv} to uncolored inventory name of current inventory of player
        replace "PackageSetting" with "" in {_inv}
        clear {package.set.%{_inv}%::*}
        set {_number} to 1
        loop 54 times:
            set slot {_number}-1 of player's current inventory to {package.set.%{_inv}%::*}
            add 1 to {_number}

also, it might be best to use a skript-addon plugin for gui/inventory things as the default skript one is very laggy and doesn't work well. I recommend using one such as skript-gui as its fairly easy to use and it works quite well.
Finally, it would be useful to update your skript version to the latest one.

PS: Please use the insert code function so that it is clearer to see the formatting of the lines