A novice is a beginner: a person who's just starting out as they learn a sport, a skill, a game, a job, a musical instrument, or some other thing.
In other words, a novice is a person who's new at what they're doing. They've just started learning, so they're not yet very good at things.
For example, when you were a novice at reading, you had to work hard to sound out words, and you went slowly and made mistakes. Later, as you got stronger and more skilled, you read faster, more easily, and you made fewer mistakes. You weren't a novice anymore.
When teenagers first learn how to drive, they are novices. They feel nervous. They make errors. They're not good at parking, and they're not good at merging onto a highway. But with lots of time, and lots of experience, novice drivers become good drivers: safe, confident drivers.
When I was a novice with my guitar, I played songs too slowly, and my fingers felt clumsy and awkward as they tried to mash down the strings to hold the chords. It took lots of time and lots of practice before I played well! If you're a novice at something, everything feels slow and difficult. But stick with it and work hard—you won't be a novice for long!