Let me give u some backgrounds....
For forty-two years after had attained enlightenment, the Buddha's wisdom, he preached the teachings of Hinayana and provisional Mahayana sutras that is accord with the capacities of his listeners or that is accord with the level of the understanding of the minds of his listeners and not the Buddha's wisdom. With all those long years he had used various similies and parables and other methods that would understand little by little the Dharma(LAW, ultimate truth, justice,code of conduct etc.). ANd the last remaining eight years of his, he finally expound his true Dharma, The Lotus sutra- the true wealth of the Buddha. He preached directly his enlightenment that is embodied on this sutra, and discarded his former teachings as only a preparatory- that is the teaching of the three vehicles.
In the "Expedient Means" cHapter makes it absolutely clear that true intent of the Buddha in teaching the three vehicles was to teach the One Buddha vehicle- that is the Lotus sutra itself. This clarification is called " the replacments of the three vehicles with one vehicle ". It stresses that the Buddha teaches only one vehicle, and that there are not 2 or 3 vehicles.
Shakyamuni gives explicit expression to the fact that there is only one vehicle, in the passage:
" The Thus Come Ones(one of the Honorable titles of the Buddha) have only a singlr Buddha vehicle which they employ in order to preach the LAw to living beings. They do not have any other vehicle, a second one or a third one.(LS2,31) "
The three vehicles are meanwhile put into their proper perspective in the passage:
" THe Buddhas, utilizing power of the expedient means, apply distinctions to the one Buddha vehicle and preach it as though it were three. "
This means, the three vehicles are a way in which the Buddha divided up the teachings of the single BUddha vehicle as an expedient means to lead people to the truth.
The "Expedeint Means" Chapter repeatedly and strongly emphasizes that the Buddha's true intent and lies solely in the teaching the One Buddha vehicle. The revelation that the three vehicles are merely expedient means and that only one Buddha vehicle is true is also called " the unification of the three vehicles within one vehicle".
In other words, it was clarified that what Buddhas now teaching is the One Buddha vehicle- that is he continued that all people regardless of social status, sex, social background etc. that all people have the potential to attain Buddhahood, or supreme happiness.Like for instance, it was phrophecied that the Learners or the voice-hearers in Chapter nine will surely to attain Buddhahood.Unlike, the former teachings they cannot attain Buddhahood Like with women. But, in the Lotus sutra teaching us that all living beings have the Buddha nature posseses inherent in our lives.