Since you are a beginner, it will take time before you can draw well
時間かかる - take time
長い時間かかる - take a long time
初心者 - beginner, novice
上手く - do well
上手く描く - draw well
初心者なのでなかんか上手く描毛なくて長い時間かかる
Since you are a beginner, it will take time before you can draw well