model.fit(x_train, y_train, epochs=80, validation_data=(x_test, y_test))

This code trains a machine learning model using the training data (x_train and y_train) for 80 epochs, and validates the model's performance on the test data (x_test and y_test) after each epoch. The fit() method is used to train the model and the validation_data parameter is used to specify the test data for evaluation. The model's performance on the test data is also monitored during training to prevent overfitting.