`shell` is the current shell from which you executed your `time` statement. `children` is a summary of all child processes started from (and still owned by) the same shell.

`user` and `system` show the amount of CPU seconds the above processes spent in user mode and kernel mode, respectively. See https://blog.codinghorror.com/understanding-user-and-kernel-mode/ for more info.

`cpu` shows the combined values of `user` and `system`, as a percentage of total CPU time. `total` shows how long ago each process was started (here in minutes:seconds.fraction).