"Is he from China?"
Translation:¿Él es de China?
There are a number of ways to enter accents depending on your system. E.g. holding down key and cycling through accent options; or using Compose/Alt-Gr key e.g. ' + E = É; or using Charmap (click Run + Charmap); if you type "acute" in "search for" box you narrow it down to all the accented letters, and also the tilde and diaeresis-laden characters are there along with characters for most languages worldwide. Of course in the web interface, Duolingo also provides buttons you can click for each of the letters with diacritic marks.
If you are responding to to audio, your response must be whatever is stated in the audio. However, if that is not the case then El es de china is masculine, and Ella es de china is feminine. So it depends on whether the subject is a male or female. Google might help you with this and so can duo lingo. Hope this helps.