When choosing pedals, you want to first determine what type is best for you. Most entry-level mountain bikes will have platform pedals. They’re ideal for beginners, as they don’t require special shoes; any sturdy shoes with a flat bottom will work. It’s also easier to get off of the bike if necessary, which is great for beginners, as well as downhill riding and dirt jumping. They’re also typically less expensive than clipless pedals, at least for entry-level models.
Clipless pedals feature a special cleat that is then attached to a shoe specifically designed for mountain biking, providing a true connection between foot and pedal. It can take beginners a bit of time to get used to clipless pedals, but they do come with their advantages. The connection can improve handling on rougher terrain and bumpy descents. They also have a smaller overall size and are typically lighter in weight than similar-quality platform pedals.