Meditation means to engage the mind in thinking of the form of the Lord, of the qualities of the Lord, of the activities of the Lord and of the service of the Lord. Meditation does not mean anything impersonal or void. According to Vedic literature, meditation is always on the form of Viṣṇu.
The Nectar of Devotion 1970 Edition
By His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
Chapter 10 “Techniques of Hearing and Memorizing”
In the Nṛsiṁha Purāṇa there is a statement about meditation on the form of the Lord. It is said there: “Meditation focusing on the lotus feet of the Supreme Personality of Godhead has been accepted as transcendental and beyond the experience of material pain and pleasure. By such meditation even one who is grossly miscreant can be delivered from the sinful reactions of his life.”
In the Viṣṇu-dharma there is a statement about meditation on the transcendental quality of the Lord. It is said, “Persons who are constantly engaged in Kṛṣṇa consciousness, and who remember the transcendental qualities of the Lord, become free from all reactions to sinful activities, and after being so cleansed they become fit to enter into the kingdom of God.” In other words, no one can enter into the kingdom of God without being freed from all sinful reactions. Sinful reactions can be avoided simply by remembering the form, qualities, pastimes, etc., of the Lord.
In the Padma Purāṇa there is a statement about remembering the activities of the Lord: “A person who is always engaged in meditation on the sweet pastimes and wonderful activities of the Lord surely becomes freed from all material contamination.”
Meditation on Executing Devotional Service More
The Hare Krishna Movement 