Word for word:
jita-atmanah — of one who has conquered his mind; prasantasya — who has attained tranquillity by such control over the mind; parama-atma — the Supersoul; samahitah — approached completely; sita — in cold; usna — heat; sukha — happiness; duhkhesu — and distress; tatha — also; mana — in honor; apamanayoh — and dishonor.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
For one who has conquered the mind, the Supersoul is already reached, for he has attained tranquillity. To such a man happiness and distress, heat and cold, honor and dishonor are all the same.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Actually, every living entity is intended to abide by the dictation of the Supreme Personality of Godhead, who is seated in everyone’s heart as Paramatma. When the mind is misled by the external, illusory energy, one becomes entangled in material activities. Therefore, as soon as one’s mind is controlled through one of the yoga systems, one should be considered to have already reached the destination. One has to abide by superior dictation. When one’s mind is ﬁxed on the superior nature, he has no alternative but to follow the dictation of the Supreme. The mind must admit some superior dictation and follow it. The effect of controlling the mind is that one automatically follows the dictation of the Paramatma, or Supersoul. Because this transcendental position is at once achieved by one who is in Krishna consciousness, the devotee of the Lord is unaffected by the dualities of material existence, namely distress and happiness, cold and heat, etc. This state is practical samadhi, or absorption in the Supreme.