An asterisk means that the file is executable. The meaning of the indicators is listed in the info page of ls. Here they are:
Append a character to each file name indicating the file type.
Also, for regular files that are executable, append `*'. The file
type indicators are `/' for directories, `@' for symbolic links,
`|' for FIFOs, `=' for sockets, `>' for doors, and nothing for
regular files. Do not follow symbolic links listed on the command
line unless the `--dereference-command-line' (`-H'),
`--dereference' (`-L'), or
`--dereference-command-line-symlink-to-dir' options are specified.