This is the 7392nd most frequent Korean word.
처음이라고
"It’s (because) the first time."
Here, '처음이라고' is used to describe something being the first instance for someone.
이 일을 처음이라고 생각하지 마세요.
Do not think of this work as your first time.
In this context, '처음이라고' expresses that it is someone's first experience with something.
마라톤은 처음이라고 해서 걱정하지 마세요.
Don’t worry just because it’s your first marathon.
'처음이라고' here refers to someone stating that this is their first time trying Korean food.