This layer takes an input and output an N dimensional vector.
Based on the activation map like curve detector with high value,
The layer take the previous layer and decides which features correlate to a specific class, in self-driving, it correlates to the different angle. Similiarly, if the program is predicting that angle is 0.5, it will have high values in the activation maps that represent high level features.
TRAINING SET: It is used to adjust the weights on the neural network.
VALIDATION SET/Test phase: in order to estimate how well your model has been trained (that is dependent upon the size of your data, the value you would like to predict, input etc) and to estimate model properties (mean error for numeric predictors, classification errors for classifiers, recall and precision for IR-models etc.)
,minimize overfitting