Biofuels directive is basically a set of rules made by some people in charge that say how much of a special kind of fuel we should use in our cars and trucks. This special fuel is made from plants instead of oil.
Think of it like this: You know how you sometimes make juice from oranges or other fruits? You take the juice out of the fruit and drink it. Biofuel is kind of like that, but instead of oranges, we use special plants like corn, sugarcane, or soybeans.
The people who made the rules want us to use more of this special fuel in our cars and trucks because it's better for the environment. It doesn't produce as many bad chemicals that make the air dirty, like oil does.
There are some rules about how much of the special fuel we need to use. The people in charge want us to use a certain amount of it every year, and they keep changing the rules to make it better.
So, the Biofuels directive is like a grown-up rule book that tells us how to suck the juice out of some plants to make our cars and trucks go while also taking care of the planet.