The languages work the same
If you wish to go beyond with a certain project or to use different languages, it is always good to learn about different basic techniques and how to think like a coder. In this way, no matter what type of skills you may have, you can use them in learning new ones. Most of the time programming languages for beginners are being modeled one after the other, so their structures and syntax are the same. Therefore, when a person learns about one, he also learns about all of them.
C code is the basis for any computer language
You can train to write efficient code by using the C, which is a widely used programming language. There are some reasons for doing this. Learning about C is the same as a medical doctor learning about basic anatomy. The C is the machine level language which teaches how the programs work with the lowest hardware. You may learn about different things such as memory management and how to debug programs or how the computer works, which you are not able to achieve with the higher level languages such as Java. C code is the grandfather for other languages, including java. C has a steeper and stricter curve compared to learning other languages, and if you plan to work with other programs which interface with the hardware, knowing about C is going to be very beneficial.
Java is a popular program at the second level, and it is the language which is typically taught in a CS programming course. Java can enforce the solid object oriented principal and it is used for different languages. When someone has mastered the language, he can learn about the OOP language much faster.
Python is easy and fun, so it is recommended for the people who have just started learning coding. It is simple, but it has greater ability. The code enforces a better programming style, and it is not that strict on the syntax. What you want to learn may depend on if you wish to learn coding just as hobby or if you wish to have a career in coding.