Having obtained the eye of wisdom,
I will remove the darkness of ignorance;
I will block all the evil paths
And open the gate to the good realms. — Bodhisattva Dharmakara
"Having obtained" refers to years of study (of the three sutras of Amida Buddha) and meditation (particularly Nembutsu or Buddha Recitation) which uncovers the "Eye of Wisdom".
"Eye of wisdom" refers to the eye that sees the Dharma and the inner spiritual world. Also known as the Dharma Eye, the Eye of Wisdom is the complement of the physical eye that sees the external material world, which is called the Worldly Eye.
"Darkness of ignorance" refers to the state of the unenlightened mind that delights in sensuous desire and the evil passions which distract the Buddhist from the spiritual journey. Evil in context with the passions refers to any confusion and distraction from that journey due to wrong action resulting in wrong-mindedness.
"Evil paths" refers to the many paths which distract the Buddhist from achieving calm abiding and peace of mind. Calm abiding refers to the mind that is content with itself and is free of evil passions.
Through regular meditation, it is possible to "remove the darkness of ignorance" and "block all the evil paths" through calm abiding and continued reflection on Enlightenment. By removing the darkness of ignorance and blocking all evil paths, confusion and distraction from the spiritual journey is dispelled. As a result, the clear mind is achieved in which calmness abides.
With calm abiding, it is possible to "open the gate to the good realms" of spiritual contentment, which prepares the way to the Pure Land of Bliss.
Juseige - Verses confirming the 48 Vows:
Eye of wisdom: http://www.buddhapadipa.org/dhamma-corner/the-eye-of-wisdom/