Ohhh a screenshot - I love to see what people's worlds and bases look like. This is so cool.
Also, nice find! Golden cows are rare livestock and much more valuable than regular dairy cows. If you have a taming rope (buy from vendors or craft), you can bump into it to attempt taming (20% success chance). Once tamed, it follows you lead it back to a fenced pasture at your homestead and it'll settle in. Then you can milk it with a milking stool for golden milk, which makes premium cheese! If you don't have a homestead yet, you'll need to find a homestead deed from a vendor to claim land first