This verse is from the Bhagavad Gita, Chapter 7, Verse 2. It is written in Sanskrit and translates to English as follows:
jñānaṁ te ’haṁ sa-vijñānam idaṁ vakṣhyāmyaśheṣhataḥ
yaj jñātvā neha bhūyo ’nyaj jñātavyam-avaśhiṣhyate ||2||
"I shall tell you this perfect knowledge and the special science with it, after knowing which, there will be nothing left to know in this world."
Explanation in detail:
In this shloka, Lord Krishna is explaining to Arjuna the importance of supreme knowledge and its special form. He says that He will give Arjuna the complete knowledge including not only theoretical knowledge (jnana) but also its practical experience (vigyan).