I recommend to you the following Apps in order to improve your German
LANGSAM GESPROCHENE NACHRICHTEN
ONLINE LERNEN mit Duolingo
If you really just need English worded grammar explanations, there are a ton of these resources online. This is the best and most comprehensive website for German grammar explained in English. She has bunch of exercises and the answer keys to go with them. It’s really brilliant: http://www.nthuleen.com/teach/grammar.html .
Also “Learn German with Jenny” on YouTube is very nice. She has some really nice video tutorials for learning German. Here is her website that also includes exercises: http://germanwithjenny.com/.
Beyond this, I’d also check Yabla which is great for audio visual content for learning German: https://german.yabla.com/
BOOK (if your native language is English)
I like the following books
• Prüfungstraining DaF: A2 – telc Deutsch A2: Dieter Maenner
• So geht’s noch besser zum Goethe-/ÖSD-Zertifikat B1: Ignatiadou-Schein…
• Mit Erfolg zu telc Deutsch B2: Zertifikat Deutsch Plus. Hans-Jürgen Hantschel
As well, I also do highly recommend the practice tests on their web pages.
– German Short Stories For Beginners: 8 Unconventional Short Stories to Grow Your Vocabulary and Learn German the Fun Way!
– Das Idealpaar
– Cafe in Berlin (Andre Klein)