You just highlight ANY word on ANY webpage using mouse (like you do for currency conversion) and Opera would translate it to your preferred language (which you could set in settings). Again, I also often buy stuff from German online shops and since my German is a bit rusty, I need to copy words to separate translation services and it's a very time consuming process. But if Opera automatically displayed a popup with translation like it does for currency conversions, it would be super useful and time saving.

And I also don't want whole page translation because that often doesn't work or breaks the page (I know I don't like the one Chrome has). But individual words, super useful. Sometimes you understand most of the stuff, you just miss that one word. Highlight it and bam, instant translation.