This is the Spanish locale* for our port of Xournal: a polished version of the .po file to incorporate into the sources, and the binary .mo file so normal users don't need to generate anything; just uncompress the archive "xournal_08d_es.zip" in the Programs folder of your SD card, start Xournal and enjoy.
*This is not taken from current sources for Xournal; I don't use it on computers, so the terms I've chosen may be a bit off or simply different from the ones you're used to. Feel free to comment on that.
BTW: there are a few seemingly hard-coded strings which were not in the .po file and thus are still untranslated, namely:
"Import Annotations only"
"Use AntiAliasing at restart"
Edit: and all the ones that report PDF export progress.
Maybe it's time for a patch 0.8e solving that?