It means that you are late! Here all the cows are lined up at the gate ready for their morning milking. Cows are creatures of habit, they like everything to stay the same and they love routine! They know and trust the people who milk them every day, and it takes a long long time for them to get used to a new person! They also know when it is time for milking – here they seem to be saying, hurry up and let us into the milking barn! (not to mention they are probably excited to eat a few mouthfuls of delicious oats…)
Although, every once in a while a cow will sleep in and I’ll have to ask her politely to get herself into the barn to be milked.