Refers to the practice of writing characters with a brush, often as a school subject or traditional art. In everyday use, it can mean both the skill and the class itself.
When I was in elementary school, I liked calligraphy class.
彼女は習字がとても上手だ。
She is very good at calligraphy.
My daughter is learning calligraphy from a teacher in the neighborhood.
When I was in elementary school, I went to calligraphy class every week.
I practice calligraphy a little bit every day.