There are two answers to this question, depending on your level of programming experience:
If you are already fluent in another programming language, then there’s no need to learn Python. You can easily pick up GDScript.
If you are entirely new to programming, then learning GDScript is going to be more challenging because you don’t have a foundation to start with. Python is very often recommended here, because it’s a good way to learn programming in general. There are many beginner courses/books/videos/tutorials out there in Python for complete beginners. Once you have a good understanding of Python, GDScript will make a lot more sense.
Though closely related, Python abd GDScript have differences too. Having said that, learning one is not a prerequisite for learning the other. You can start with GDScript, which provides more concrete examples to try and wrap your head around, and then you can move on to Python which will allow you to create more practical applications. In fact, I do not think you need to have any prior experience with any programming language to pick up GDScript. It could well be your first programming language, because it is intuitive, well-documented and easy to use. Plus, if you learn GDScript first, you may find the transition to other languages way smoother and effortless.
It seems like you have little to no experience with programming, so I suggest you start simple. Open up a new project in Godot and try to output a few values on the screen, like the sum of two numbers. Then, when you are comfortable with the basics, like variables, functions and methods, you can start a mini project, like a small game. There is a plethora of examples to help you learn and the community is willing to assist you too. Make an asteroids game or even a candy crush style game, if you are daring enough.