Let's look at your sentence: "I’m not afraid of heights. I hop in steep rocks."
First, it's great that you want to tell about climbing or jumping on tall rocks!
But to make the sentence sound better, here are two small fixes:
- Instead of "hop in steep rocks," we say "hop on steep rocks." We use "on" when we are standing, jumping, or playing on something.
- So, the sentence becomes: "I'm not afraid of heights. I hop on steep rocks." This sounds clear and correct!
Good job, and keep practicing your sentences!