This is a teacup subcommand. It reports or sets the amount of time that teacup will wait for any particular file to be loaded from any repository.
DKF: Note that as of writing, the largest file that you will have to commonly download is the metadata database when updating the cache, which is currently about 12MB compressed. Since the default timeout is 30 seconds, you'll have cache problems if your download bandwidth is 4Mb or less. Fix them by raising the timeout...