There are a few ways to get a quick word translation.
Word Translation on Double-click
Double-click on the word with the mouse to see the translation. Pop-up Bubble window opens with available translations.
To enable this feature go to the Pop-up Bubble Options and check the option "Translate on double-click".
Don't forget the Save options to record your changes.
Word Translation with a Shortcut
Hold the ALT key while highlighting a word. The Pop-up window opens with the word translation.
Word Translation without a Shortcut
Disable the shortcut in the Pop-up Bubble Options.
Then, select a word with the mouse, the Pop-up Bubble window displays an instant translation without pressing or holding any key.
To enable this mode, remove the Shortcuts from the Pop-up Bubble Options by clicking on X sign, and then Save Options.
To access Options click the Options link on the Pop-up Bubble Translator.
Note: This translation mode is not recommended because it may interfere with other tasks where you make text selection with the mouse.