Knitting looks like it needs a whole toolkit of skills, but it comes down to one motion: pulling a new loop of yarn through an old one. A first square uses that and nothing else, plus a way to start and a way to fix a slip.
Your first day
Use medium-weight yarn (worsted, often labelled 4) in a light color, since dark yarn hides the stitches, with medium needles around 5 mm. Cast on twenty stitches by watching a video: search 'long tail cast on beginner' and pause after each step. Watching it twice is normal. Knit every stitch across the row (search 'how to knit for beginners' and copy the motion), turn the work, and knit every stitch back across. Stop after five rows today, and keep going over the next few evenings until the square is roughly as tall as it is wide. If a stitch drops, don't panic, but fix it soon with a small crochet hook, since it will run down the fabric if left alone.
Most beginners grip the yarn too tightly out of nervousness, which makes stitches painfully hard to slide the needle through. That's a common reason hands cramp and people give up in the first hour. Loosening the grip fixes most of the physical difficulty almost immediately.
The thing most people miss
A dropped stitch feels like the whole piece is ruined, because knitting is a chain of loops and a dropped loop unravels the ones below it. It isn't ruined. A small crochet hook, a couple of dollars at any craft store, picks the stitch back up in a minute or two once you've done it a few times, and the fabric usually looks the same afterward.
Once you know that, a mistake is a pause and not a reason to start over, which is what lets a first square get finished.
How you'll know it's working
Your stitches should slide along the needle without a fight, and the fabric will look slightly loose and uneven rather than stiff. Uneven is fine at this stage. That's simply what a first square looks like.
The purl stitch, the second basic stitch, is the natural next thing to learn. Alternating knit and purl rows makes the smooth, flat fabric you see on most sweaters.