So, for machine learning the best option would be Python(very many people use it, because TensorFlow and wide selection of other libraries) or c++.
For web development you must know html, css AND any other language(Python, go, javascript, php, c#...)
For making smart contracts great option would be GO, also may be C++, Python, C#.
It is better not to limit yourself to one programming language, but you are newbie. Based on your preferences I would start learning Python or GO. Yet better choose everything yourself, good luck
