English isn't my native language as well. So naturally when I started training it was like gibberish to me. I thought I would never get it. As luck would have it my instructor at that time was Japanese and he understood what I was going through. He recommended liveatc.net. It did wonders to me and pretty soon I knew how to communicate with ATC. Also tell your student to join aopa, at least it's free for the first 6 months. They have an excellent interactive course about communicating with ATC (along with a whole lot of others goodies as well). Flying an aircraft is overwhelming for a beginner and adding ATC to the workload can be exponentially stressful so just like anything else in flying, practice and good practice should do it.