For beginners in programming, I would not suggest learning new languages. Learn what is absolutely essential to get your idea up and running with the least amount of moving parts. In most cases, something like Python & Django will get you there. Once you feel comfortable translating ideas to life, that is when I would start exploring other languages. It's similar to learning to play music instruments, get comfortable making music through one instrument and then dive into learning new ones.
Why & when you should learn about new languages?
New programming languages sometimes have a new paradigm or a new style of thinking. This is the primary reason why I would suggest learning new languages.
For example, if you have been a python programmer throughout your life like myself. Learning Rust will introduce to the concepts of ownership & systems programming. Learning Haskell will make you appreciate functional programming and truly understand immutability and its advantages. Some languages require a completely new style of thinking, and exploring them will make you a better programmer.