-a tells the FileZilla client where local files work should be done. That is, it's where files should be downloaded to or uploaded from by default (if no specific paths are used in the transfer command itself).
It's expects a path to a folder.
From the FileZilla documentation:
Sets the local site (left-hand side) to the given path.
Use double quotation for paths with spaces in them.
FileZilla isn't intended to be scripted (their goal is to be a GUI client), so there's no way to specify files to transfer from the commandline.
Perhaps look into using Windows' in-built
FTP.exe for scripting.
Transfers files to and from a computer running an FTP server service
(sometimes called a daemon). Ftp can be used interactively.
FTP [-v] [-d] [-i] [-n] [-g] [-s:filename] [-a] [-A] [-x:sendbuffer] [-r:recvbuf
fer] [-b:asyncbuffers] [-w:windowsize] [host]
-v Suppresses display of remote server responses.
-n Suppresses auto-login upon initial connection.
-i Turns off interactive prompting during multiple file
-d Enables debugging.
-g Disables filename globbing (see GLOB command).
-s:filename Specifies a text file containing FTP commands; the
commands will automatically run after FTP starts.
-a Use any local interface when binding data connection.
-A login as anonymous.
-x:send sockbuf Overrides the default SO_SNDBUF size of 8192.
-r:recv sockbuf Overrides the default SO_RCVBUF size of 8192.
-b:async count Overrides the default async count of 3
-w:windowsize Overrides the default transfer buffer size of 65535.
host Specifies the host name or IP address of the remote
host to connect to.
- mget and mput commands take y/n/q for yes/no/quit.
- Use Control-C to abort commands.