A musician is someone who plays an instrument. It doesn't need to be professional. All singers are musicians because the throat is an instrument. However, not all singers can play an instrument apart from that. Some can't even read sheet music. When I was growing up, some of my favorite singers played other instruments. Alicia Keys and Amy Lee (from Evanescence) are some examples. I remember watching them perform on stage with their pianos. Both have different styles of music, different voices, and both masters at the piano. Both of these women have been playing the piano for most of their lives.
I wanted to be like that. I thought, "playing an instrument makes you a real musician." Even if you don't play another instrument, being a singer makes you one. You can create music, even if you don't read it. I started out on a keyboard my parents bought not long after I was born. I have it now in my apartment (still works!). I didn't know what I was doing back then, of course. I just played with the settings to see what sounds I could make. I eventually talked my mom into signing me up for lessons. With a scholarship, it didn't cost her anything.
When I took lessons (piano and voice), I learned with classical music. Learning operas and folk music as a foundation. I've taken lessons, for more modern styles as well but I think classical helps the most.
Fast forward to today, I play the piano, flute, and the guitar. I started as a teen, so I haven't mastered anything yet. My goal in this is to learn as many instruments as possible. My next one will be the Violin. My sister has played for years, and I love the sound of string instruments.
I also want to learn drums. Sheet music for percussion instruments is different from others. I don't understand it but, someday I will.