Prabhupāda: You can read the purport also.
Pradyumna: "These sacrifices may be fitted into various divisions. There are persons who are sacrificing their possessions in the form of various kinds of charities. In India, the rich mercantile community or princely orders open various kinds of charitable institutions like dharma-śālā, anna-kṣetra, atithi-śālā, anāthalaya, vidyāpīṭha, etc... In other countries too, there are many hospitals, old age homes and similar charitable foundations meant for distributing food, education and medical treatment free to the poor. All these charitable activities are called dravyamaya-yajña. There are others who, for higher elevation in life or for promotion to higher planets within the universe, voluntarily accept many kinds of austerities such as cāndrāyaṇa and cāturmāsya. These processes entail severe vows for conducting life under certain rigid rules. For example, under the cāturmāsya vow the candidate does not shave for fours months during they year, July to October, and does not eat certain foods, does not eat twice in a day and does not leave home. Such sacrifices of the comforts of life is called tapomaya-yajña. There are still others who engage themselves in different kinds of mystic yogas like the Patañjali system for merging into the existence of the Absolute, or haṭha-yoga or aṣṭāṅga-yoga, for particular perfections. And some travel to all the sanctified places of pilgrimage. All these practices are called yoga-yajña, sacrifice for a certain type of perfection in the material world. there are others who engage themselves in the studies of different Vedic literatures, specifically the Upaniṣads and Vedānta-sūtras, or the Sāṅkhya philosophy. All of these are called svādhyāya-yajña, or engagement in the sacrifice of studies. All these yogis are faithfully engaged in different types of sacrifice and are seeking a higher status of life. Kṛṣṇa consciousness is, however, different from these because it is the direct service of the Supreme Lord. Kṛṣṇa consciousness cannot be attained by any one of the above-mentioned types of sacrifices but can be attained only by the mercy of the Lord and His bona fide devotee. Therefore, Kṛṣṇa consciousness is transcendental."
Prabhupāda:
- dravya-yajñās tapo-yajñā
- yoga-yajñās tathāpare
- svādhyāya-jñāna-yajñāś ca
- yatayaḥ saṁśita-vratāḥ
- (BG 4.28)
So charity, or sacrificing your possession for the benefit of others, this is also yajña. But they are called karma-kāṇḍa yajña, fruitive activities. By such performance of yajña, one can elevate his material position.
Just like feeding the poor. It is also yajña. But the same thing, if it is dovetailed in consciousness, that becomes perfect. People are very much inclined to feed the poor with sumptuous food, but it can be done in a little different way, that the foodstuff offered to Viṣṇu, prasāda, that distribution foodstuff is better than ordinary distribution of foodstuff. Ordinarily, that is puṇya, pious activities, but when it is connection with Kṛṣṇa, this is called yajña. Dravya-yajña. To distribute food and cloth, that is called dravya-yajña, but yajña can be said when it is done, dovetailing the activities with Kṛṣṇa consciousness. That is yajña. Yajña means Viṣṇu. Yajñārthe karmaṇo 'nyatra loko 'yaṁ karma-bandhanaḥ (BG 3.9). So our the Kṛṣṇa consciousness movement, we are also distributing food in our about one hundred branches all over the world. But not directly, but through nirbandhaḥ kṛṣṇa-sambandhe yuktaṁ vairāgyam ucyate.