I assume you're seeing this host% in documentation. It stands for the shell prompt. ("Shell" is the program that reads the commands you type; "prompt" is the little bit of text that this program displays on your screen to say that it's ready to read your next command.)

If you look at a terminal window on your computer you'll probably see something like

my-computer-name%

on the last line, where "my-computer-name" is of course your computer's name. This is prompting you (i.e., inviting you) to type a command. So now you go and type ls and carriage return, and the shell prints some output.

Linux documentation typically uses host% to indicate the prompt ("host" is another name for "computer").

This host% It's not meant to be typed: it just indicates that what follows in the document is to be typed.