If you're trying to improve your musical ear, then you've probably heard about solfegé. Solfegé, or solfeggio, is simply the act of singing musical notes using syllables such as do, re, mi, etc. Sightsinging using these syllables can help you improve your musical ear and become a better pianist since you'll hear more in your music. It will help your improvising too, since you'll be better able to translate the sounds you hear in your imagination onto your instrument.
There are several systems of solfegé and I sometimes get emails asking me which one is best. This is a great question and when I read these questions I'm always reminded of a funny incident from my college days.
One day, a bunch of us music students were sitting around, debating which solfegé method was best (fixed do, moveable do, singing on la, note names, etc.) The conversation got quite animated as we students debated the pros and cons of all the various methods. We probably would have gone on for hours if we weren't interrupted by a passing faculty member. The professor listened to us for only a brief moment before he said, "Well, the systems are all good, provided you actually practice the one you choose!"
We knew we had been outclassed. He was absolutely correct! He was also implying that as much fun as it was to sit around and talk about ear training, we should have been in our practice room actually doing it. Lesson learned!
So if you're interested in learning solfegé, then yes, check out moveable do, fixed do, and any other system you're interested in. They all have their own advantages and disdvantages. ("Fixed do" doesn't place do as the tonic in each key. "Moveable do" breaks down when the music modulates, etc.) But at some point you need to choose one and spend time with it. Lots of time so you can learn it inside out until it becomes second nature. Have fun and enjoy the progress your musical ear makes.
Ear training and improvisation go hand-in-hand. Here are some free piano improv lessons that are fun and will improve your musical ear!