Because it's correct! This is the standard word order for question forms. 1. Question word : What... 2. Auxiliary verb: ...does.. 3. Subject: ...this word.. 4. Main verb: ....mean? Here are some more examples of this pattern in the simple present and simple past: Where do you live? How does she feel? What did he say? Why didn't you answer? We also use the same pattern (Question word + Auxiliary + Subject + Main Verb) for different tenses/aspects/moods: What are you doing? What have you seen? Where was it made? The same pattern is also used with modal verbs: What can I say? Where will they go? Who should I see? The only exception is in the case of subject questions, where the question word (What/who) is also the subject of the sentence. Common examples of this question type is 'What happened?' or 'Who wrote that book?' Remember that the grammar/word order of English sentences is not necessarily the same as in Portuguese, so you shouldn't assume that you can translate something word-for-word from one language to another. I hope that helps.

it's just a different order of words to say French for example. In English we say, what does this word mean?, or - what does that word mean?.