This verse is from the Bhagavad Gita, Chapter 6, Verse 11. It is written in Sanskrit and translates to English as follows:
śhuchau deśhe pratiṣhṭhāpya sthiram āsanam ātmanaḥ |
nātyuchchhritaṁ nāti-nīchaṁ chailājina-kuśhottaram || 11 ||
"In a clean place, having established a firm seat for oneself, neither too high nor too low, and covered with cloth, deer skin, and Kusha grass."
Śhuchau: Pure or clean
Deśhe: Place
Pratiṣhṭhāpya: Having placed or having established
Sthiram: Steady or firm
Āsanam: Seat or posture
Ātmanaḥ: Of oneself
Nā: Not
Ati-uchchhritam: Too high
Nā: Nor
Ati-nīcham: Too low
Chailājina-kuśhottaram: Covered with cloth or deer skin and Kusha grass