> sign is used for redirecting the output of a program to something other than stdout (standard output, which is the terminal by default).
>> appends to a file or creates the file if it doesn't exist.
> overwrites the file if it exists or creates it if it doesn't exist.
In either case, the output of the program is stored in the file whose name is provided after the redirection operator.
$ ls > allmyfiles.txt creates the file "allmyfiles.txt" and fills it with the directory listing from the ls command
$ echo "End of directory listing" >> allmyfiles.txt adds "End of directory listing" to the end of the file "allmyfiles.txt"
$ > newzerobytefile creates a new zero byte file with the name "newzerobytefile" or overwrites an existing file of the same name (making it zero bytes in size)