"i" before "File" represent a prefix before the name of the variable. you can declare variable names how you want, but using that prefixes would help you to code faster
integer -> new iFile
string -> new szFile[64]
float -> new Float:fFile
boolean -> new bool:bFile
global integer variable -> g_iFile
and so on
probably supremache didn t paid enough attention or he just copied the code from another plugin, but the g_szFile[128] should be szFile[128] because it s not a global variable and it is a string where the file path is stored.
PHP Code:
new iFile = fopen( g_szFile, "rt" );
here, native fopen return file pointer (it s like a identifier for the specified file, if you want to see what fopen parameters do, you can read here:
https://www.amxmodx.org/api/file/fopen)
the g_szMessage is a global variable where the message is stored after the plugin read it from the file. as you can see, he declared the variable above the plugin_init and because is not declared in a function the variable is global