It means - To offer all our Karmas to Ishvara. That would rid the mind of the ego, of doer-ship, of tensions and stress and thus it helps in Atmadarshan. The best example is of Sri Girishchandra Ghosh who was asked by his Guru, Sri Ramakrishna Paramahamsa, to offer all his deeds to him and that purified him, elevated him. (read attachment)
Ishvarpranidhana helps in reducing the ego and helps us, to be a harmonious part of a team and to work in a team. Thus a real practitioner of Yoga is a good team-member as his/her 'I' is absent.
By practice of Ishwarpranidhana, one attains Samadhi, Self realization, realization of Oneness.
Mananeeya Eknathji wanted each of the Karyakarta to understand all these Yamas and Niyamas which are very essential for the Anushasana that one needs to have in oneself and also while working in society. It would create lot of stress in the beginning as the one who has fixed his goal would find it difficult to practice. But Purity, Patience & Perseverance alone works and so devotedly working would be needed.