I want to add to my Android app API for lyrics. Can I use this one:https://wiki.musicbrainz.org/Development/XML_Web_Service/Version_2
Does it support a real-time sync with the track? Can I get a word by word marking?
We don't store lyrics at all, so you'll probably need to license them somewhere else (they can be pricey, with https://developer.musixmatch.com/ starting at $25k/year, but there might be places with cheaper plans for new users).
In addition to @reosarevok's answer, you should also note our data license:https://musicbrainz.org/doc/About/Data_License
If you're going to make money from the app (ie., has user payments or ads) and you end up using our data, you should really get in touch with @chrisskye to discuss licensing.
MusicBrainz does store links to lyrics pages, so I suppose you could use MBIDs to find those, and then get the lyrics from the linked page. I doubt it would be a very useful approach, though.