저는(I'm) 한국어(Korean) 연습하러(to practice) 한국에(to Korea) 왔어요(came). '저는' is not necessary, so you just can say "한국어 연습하러 한국에 왔어요"

It's a very unique that a subject is not a necessary component in Korea sentence in many cases, which is often explained by the cultural context that Koreans tend not to refer to themselves directly.