अनन्यचेताः सततं यो मां स्मरति नित्यशः। तस्याहं सुलभः पार्थ नित्ययुक्तस्य योगिनः ॥

ananya-chetāḥ satataṁ yo māṁ smarati nityaśhaḥ tasyāhaṁ sulabhaḥ pārtha nitya-yuktasya yoginaḥ

He who constantly thinketh upon Me, not thinking ever of another, of him I am easily reached, O Pârtha, of this ever-harmonised Yogî.

In plain words: Krishna says that a person who thinks of him all the time, and never lets the mind drift to other things, reaches him easily. Arjuna is called Partha here, meaning son of Pritha.