Are you referring to freshman in high school or college?
The topics covered in high school and college are essential the same but at the college level it's more in details and depth.
The challenging thing about taking a biology course is the laboratory. In taking to my classmates from biology class (in high school and college), I realized that no one is good at both the course and the lab. If one thrive at the content taught in class then they suffer with the lab or vice versa.
Below I've included study guides and practice problems in biology for you to study or prep yourself. Good luck!
Pigtoria is correct: biology lab and/or class can be difficult. Anyone who is thinking about a science field of study in college will most likely need the "Big 3": bio, chem, physics. If you are thinking about taking the AP bio course in HS, you definitely want to take an honors bio course first. The AP course, just like in college, moves faster and is deeper in terms of knowledge and concepts. The advantage of an AP course is that MOST colleges will offer at least SOME credit for the AP course if you do well on the exam at the end of the year. This means you will be ahead in college credits and may even be able to avoid the subject in college once there (provided it is not directly tied to your major).
It's hard to answer this question without knowing your level of talent in science. However, speaking from my own experience, I'd say Biology isn't really easy OR hard for high school freshmen -- it seems right on track. Just to give you some perspective, my high school, for some crazy reason, did the science program in reverse order (compared to most schools): we took physics in sophomore year, chem in junior year, and biology senior year. Since I am someone who is not at ALL skilled in science/math-related subjects, being thrown straight into physics was incredibly hard for me. However, once I got to biology, it was a breeze! I suppose this was supposed to be some kind of reward for struggling through Physics and Chemistry, but I think there is a reason it's usually taught Bio first, then Chem, then Physics...there's a very clear progression from one subject to the next.
Anyway! Enough of my yammering. I'd say, if you're already pretty good at science, or even just curious about nature and the world around you, I'd suggest taking an AP or Pre-AP course in Biology. Biology isn't heavy on the math, so it's much easier to grasp for those who aren't great with numbers but are better and understanding "concepts" rather than "facts", and should be very easy to understand for a high school freshman.
Biology is not hard and for the freshman in the subject can start by understanding the basics concepts like biosphere, food chain, pyramids of mass, number etc. All the basics concepts which needed for all the chapters can understand first.
Biology is one of the important branch of Science. Which is further divided into two Botany and Zoology. According to me biology is not a difficult subject for a freshman instead it is really interesting subject to study.