It's an interesting way to help Google Translate become more accurate. Here's what you need to do: "In the translated sentence, select the words which mean the highlighted word in the original sentence."
It's likely that all the texts from this experiment are used to train Google Translate and they include professional translations. This might help Google Translate improve the word-level alignment of Google's parallel corpora.
For the English to German pair, you can change the task to "Select all good translations of the following term":