What programming language should I learn in 2018?
Actually I answered same question for year 2017 which you can read in "Related Questions" section. Most of things didn't change dramatically, but this time I would answer differently, because answer to this question a lot depends who is asking the question.
If you are new to programming, short answer would be: Any programming language would work. Because main concepts of programming languages are same. As you know foundation of programming is Algorithms and Data Structures. You can write those algorithms in any language.
It you are learning programming to get good paying jobs, I would advice learn COBOL, it's an old language, but there is tons of legacy code written on that, programmers that know COBOL getting older, but companies don't want to rewrite whole code base that's why they search for younger people that would like to support that. It's not fun, you wouldn't use it for new projects, but it pays well.
If you know few languages and want to learn more, here is some statistics for you, there is a index called "Tiobe index for Top programming languages" - they release each year on December, for 2017 December their list is following:
There is a popular job marketplace called Indeed. They have another list called Most In-Demand Languages, for December 2017 list is following: