Welcome Finnish Flyer,
What Jan said. Forget the phone, look out the window as much as you possible can, it's what you're paying for! Remind yourself that many of us learned to fly before "technology" was even thought of, and we did perfectly fine. I'm not saying that technology is of no use, but I will say that every minute you spend being distracted by a gizmo during your early flight training, is a minute that you paid for, that you did not use to learn about flying! You have lots to think about and learn just looking out the window, so do that first. Leave your phone in your pocket the entire flight.
To more directly answer your question, the phone may slightly interfere with the airplane radios. You may hear a little "bip bip bip" sound every now and then. It may be distracting, but won't bother visual flying in a GA plane.