What does the @ sign and the number next to it mean in ls -l display?
The "@" means that the file has extended attributes.  You can see them with the xattr command.  The "1" is the number of links to that file.  In most cases, for normal files, this will be "1".  For directories, it is the number of files/subdirs + 2 (the two actually represents the directory itself, and the parent directory).