( sleep(1) 10 ; echo(1) "hello world" )
(list) list is executed in a subshell environment (see COMMAND EXECUTION  ENVIRONMENT  below).   Variable
       assignments and builtin commands that affect the shell's environment do not remain in effect after
       the command completes.  The return status is the exit status of list.
delay for a specified amount of time
Commands separated  by  a ; are executed sequentially; the shell waits for each command to terminate in turn.  The
return status is the exit status of the last command executed.
display a line of text
Echo the STRING(s) to standard output.
source manpages: sleepecho