moterm is an application that provides an embeddable view, which provides a VT100-style terminal that its embedder can connect to other applications. It is not useful as a standalone application (embedded by something, like a window manager, that is not aware of how to control it).
For an example of an embedder that's useful as a standalone application, see the Moterm example application.
moterm exposes the mojo.terminal.Terminal interface to its embedder. Via this interface, its embedder may connect to the terminal directly (for direct input/output with the terminal) or request that the terminal connect to another application. In the latter case, that application should implement the mojo.terminal.TerminalClient interface.
Output to/input from the terminal is done via a mojo.files.File that behaves “like a terminal” (in much the same way as in Unix one has terminal device files and file descriptors to them).