In plain words

A command is a short typed instruction.

The shell is the waiter. You say pwd. The waiter takes it to the kitchen. You are not writing a program file yet. You are asking for one action now.

Same buttons as Stage 3. Use them here as a dictionary.

A little deeper

What && means

pkg update && pkg upgrade means: do the first job, and only if it works, do the second. A chain, not two mysteries glued at random.

Command not found

The tool is not installed, or the letters are wrong. The computer is not angry. It cannot guess.

Package versus app

pkg install puts a tool inside Termux. The Play Store and F-Droid put apps on the home screen. Same idea, different room.

Python is where those commands start running files you wrote.

Python is the first language in this school.

Kinds of code Python