net user 显示结果不懂 菜鸟请教~

我连接上一台SA空口令的肉鸡，我查他的用户net user他显示结果
C:\>net user
The command USER is unknown. For a list of valid commands, type NET HELP at
the command prompt.
For help, type NET /? at the command prompt.
请问是什么意思啊，谢谢