There are LOTS of languages. Picking one (or two, or three!
iOS/Android (React Native), Backend Web Dev (Node), Embedded systems, Front End Web Dev (Angular/React), Scripting. It runs everywhere.
An answer to this question highly depends on what your background is and why you want to learn a programming language. Are you trying to make mobile apps, websites, art, tools for yourself...?
There are several beginner friendly languages out there, and with the amount of tutorials and guides, it's easier than ever to learn most "popular" ones. That is if you put the work in it...the basic concepts are a bit harder to grasp for beginners, but with practice they become your second nature.
I think the most beneficial for me was the combination of HTML+CSS+JS. That gave me the baseline of:
- how to structure things in code (elements in HTML)
- how to make them visually pleasing and behave in a way I want (styling, positioning and animation in CSS)
- how to bring them to life (clicks, data, interactions in JS)
That being said, I've tried React, Vue and now slowly getting into Svelte, and the basics of JS help so much when learning those. The basics concepts are mostly the same in most of the newer languages, so getting this right is my focus now. (I must say that I'm no developer, though I've developed several iOS apps and websites from scratch, so take what I write with a grain of salt :P)
I'm in a similar situation. I learned to code because I wanted to know what my limitations as a designer were when designing sites: Semantic HTML, CSS (Flex and Grid), and some JS (though that's my weakest language and still requires tons of Google-ing for me). After a couple of years of trial and error, I've began learning React and the basic fundamental knowledge I had for JS helped speed up the process for React. I now design and prototype with code and have been told by multiple developers that they appreciate having a designer that understands the fundamentals of web development and not presenting blue-sky designs like they are used to. I wouldn't call myself a developer either, but on my resume I do have something along the lines of "UX/UI Designer with a fundamental understanding of front-end languages." I would recommend all UI Designers take some courses on front-end languages — it'll raise your stock in a lot of people's eyes.
Ruby or python are very beginner-friendly. Codecademy is a great place to learn https://www.codecademy.com/
The other comments are great. Here’s another option: Processing. It’s a brilliant way to augment design tools. It’s very beginner friendly. There’s tons of resources for learning and the official reference docs are good.
Processing is brilliant and what I originally learned to code with, but I would say P5 https://p5js.org/ its better maintained, you can actually send what you make to people easier and it can be integrated into web pages.
I'd only use Processing these days if I wanted to interface with circuits or hardware.
It's easy, versatile, fast and the syntax is pretty close to anything else you'd be likely to want to learn, unlike Python.
If is it backend development: Python 3+, Golang, PHP 7+