A butrón is the Spanish term for a hole deliberately made in a wall, ceiling or floor to get into business premises or a home without going through the door. That is exactly the point: to bypass the lock when the door is strong.
It tends to happen in shops and commercial premises next to another empty unit, a garage or a storeroom, and in homes that adjoin areas that are not in use. Houses and premises that stay shut for long periods are more exposed, because nobody hears the noise.
Against a butrón the lock is not enough: you need to look at the whole picture, which walls back onto empty spaces and how each way in is secured. We go over it with you in security upgrades.