This verse is from the Bhagavad Gita, Chapter 6, Verse 18. It is written in Sanskrit and translates to English as follows:
yadā viniyataṁ chittam ātmanyevāvatiṣhṭhate
niḥspṛihaḥ sarva-kāmebhyo yukta ityuchyate tadā ||18||
"When a person's mind is completely controlled and situated in the soul, and that person is free from all worldly desires, then only he is called a yogi".
This verse explains the state of a true yogi, whose mind is controlled and who is detached from worldly desires.
yada - when
viniyatam - controlled
chittam - mind (state of mind)
atmani - in the soul, in the self-form
eva - hi
avatiṣthate - is situated
nisprḥah - without desire, free from all desires
sarvakamebhyaḥ - free from all kinds of desires
yukta - unified, yogi
iti - so
uchyate - is said
tada - then