Hi and welcome to watercolour! You've gotten good advice, above. There are a lot of resources, here on Wet Canvas. If it's within your budget, Artist Quality paint and 100% cotton paper are the most important things. Even just four tubes of paint (maybe three primaries and a burnt sienna) can get you started. Any brand is fine, but strictly from a personal standpoint, there are three brands that I would not recommend to beginners: QoR, because it is a little odd and not quite a typical watercolour experience; Marimeri, because every one that I have tried by them was plasticy; and Winsor and Newton, because I find their tubes hard to rewet and their business practices/quality control to have gone down hill in the past several years. You will use a lot less paint than with oils, so these small tubes will last you a long time and paint that has dried on your palette can just be rewet and used. You will have to decide between pans and tubes to start. Note that you can fill pans with tube paint and tubes are usually more economical per ml. But with so many things to consider, a lot of people start with a little pan set, just because it seems easier. Pans generally work better for smaller brushes, so if you want to paint large, I would go with tubes and a cheap plastic palette or white dinner plate to squeeze them onto, depending if you will be only working at home or taking them out into the field.
It's usually easiest to work on all cotton, cold-pressed paper. That is the middle roughness and classic watercolour effects work well on it. 140 lb. is a good starting weight. A lot of beginners are put off by the price, but a full sheet can be torn or cut down into smaller ones and you can paint on the front and back, if you like. I like Fabriano Artistico, because of the consistent quality, texture, and that it doesn't have animal sizing, but I don't think there is a 100% cotton paper that is notorious for being terrible. It's definitely personal preference and you can decide, with experimentation.
You will need something to attach your paper to, a board or some kind, preferably waterproof. You can tape it or staple it. Many of us don't bother stretching paper first, but others find the process worthwhile. You might want to have something with which to prop your board up, but that could be a book, a brick, whatever you like, unless you are using an easel. I just tape my paper to my glass-topped drafting table, when I am sitting at it or a sheet of plexiglass, when I need something more portable or have several paintings going at once. You'll need a water container for rinsing your brushes, and a cloth (or paper towel, or rag) to wipe off your brush. Some people like a spray bottle or pipette to put clean water onto their paints. I recommend having a sketchbook that accepts washes, to test out mixes and goof around in, but I love sketchbooks and I know they aren't for everyone. Strathmore makes a nice all cotton mixed media one (with a tooth more like hot-pressed paper) and I think they just came out with a watercolour one.
I hope you find a good starting set up and that you enjoy watercolour. Feel free to ask questions. We love talking about supplies!