Translation of Zaubertrank

My boss offered it to me, so that a few more people at work will have a good level of English and now I really have to kick my own ass (I've started last year and it's not going very well).
I met the company last autumn, because the site's traffic is getting pretty big and they invited me to a workshop. They have convinced me that I have to put their logo at the top of the page to maximize exposure and this was a big mistake.
I understand your English, it's not bad at all. Yes, the English vocabulary is much larger than the German. The more you might spend time using the language, the better your vocabulary knowledge will become.