We use Ctrl+V to paste stuff from clipboard, but this is not working on terminal window.
What is the keyboard shortcut to paste on the GNOME terminal?
You have to use Ctrl+Shift+V to paste into a terminal. Copy is similar; use Ctrl+Shift+C to copy from a terminal.
Arild's comment explains (edited a bit):
Following tradition, some Ctrl+(letter) shortcuts are mapped to entering control characters in the terminal (see How control characters map to keyboards on Wikipedia). That's why we cannot use them for copy and paste. The shortcuts can be overridden in Edit > Keyboard Shortcuts, but especially Ctrl+C is useful to keep assigned to the control character ETX, which is used to interrupt the current command.
Like said by others, Copy is CTRL + SHIFT + C and paste is CTRL + SHIFT + V as opposed to a normal text field.
So in short, just add shift to many other text editing shortcut to use it in the terminal.
Here are a couple examples:
Copy: CTRL + SHIFT + C
Paste: CTRL + SHIFT + V
Find: CTRL + SHIFT + F
Close terminal window: CTRL + SHIFT + W
Close all terminal windows: CTRL + SHIFT + Q