Lyrics training is a free app that claims to improve your ability to recognize the different sounds in your target language. Through listening to different songs, you can reinforce vocabulary, expressions, and grammar concepts. Although it does not provide any translations or explanations for these skills, it does seem to train listening comprehension and memorization.
While listening to your chosen song, you will be provided with a choice of 4 words to help fill in an increasing percentage of lyrics; by the advanced level, you will be responsible for filling in 100% of the lyrics. Each of the 14 languages available seem to have a wide variety of song choices, and even if you don’t understand what the lyrics mean, you will probably be able to sing along.
If you would prefer an app that focuses more on comprehension, vocabulary, and grammar, check out Lirica.