K Nearest Neighbour machine learning algorithm is considered as a lazy learner because when training data is provided to KNN, it doesn’t do any computation except storing the data. All the work is done while scoring on test data.
When training data is passed through the KNN algorithm, it saves the data. Let us consider the below scatter graph represents the training data.
When new data comes, its distance is calculated with the training data points to find the predictions.
The complete working of KNN is available here.