Where can I find the terminal on a MacBook Air 2011
By default, spotlight should find all apps (command space) if you don’t know where they sit.
The terminal app is in /Applications/Utilities
Also, the help menu works if you search for terminal, it’s not the top hit, but you should see an article covering apps included with macOS. This user guide has links to open each app (including terminal.app) and very helpful summaries of what they do.