The smbclient command is used to access shared resources on a network that uses the SMB (Server Message Block) protocol. To list the available SMB shares on a remote Samba server, the correct invocation is smbclient -L <server_name>. Here, -L stands for "list" and <server_name> is the name of the Samba server. Therefore, smbclient -L FileSrv1 will list all the available SMB shares on the server named FileSrv1.
Reference:
smbclient man page
Samba: smbclient Command