it is an egg made of flax seed
A flax egg is an egg substitute that you can often use when following a recipe that calls for an egg.
Here's the entire recipe:
Mix 1 tbsp ground flax seed and 2 - 2.5 tbsp water. Mix it up and let it sit for 3 - 5 minutes until thick and goopy.
There is no step 2.
Now if you try to use this to make scrambled eggs or fried eggs, you're going to have a bad time. It's not that kind of egg substitute.
But if you're making muffins or pancakes or waffles or bread that calls for an egg, you can use a flax egg as a one-to-one substitute.
It doesn't bind quite as well as a bird egg. So you might add a little extra binding like some ketchup or breadcrumbs in something like a bean burger patty if you're worried about that.
It doesn't have the fat content of an egg yolk. So if you're concerned about that, add a little extra oil.