From Rigpa Wiki
Nyenpa (Wyl. bsnyen pa) — the first phase of sadhana practice. The word nyenpa in Tibetan implies 'familiarization', 'associating with', or 'approaching', and is often translated as 'approach'. Khenpo Chemchok explains that "this phase of the practice is called nyenpa, or ‘approach’, because it brings the deity’s wisdom mind into your mind, through your becoming intimately familiar with the deity."
Kyabje Sakya Trizin and Alak Zenkar Rinpoche explain that: in the past, the approach practice mainly involved focusing on the visualization of the deity during the session, and the mantra was recited in between sessions. However nowadays mantra recitation is the standard practice to measure deity meditation (most of our sadhanas advise reciting a certain number of mantras for the different phases of the practice, such as the four stages of approach and accomplishment). This is why Buddhist practitioners today use the word ‘recitation’ or talk about ‘doing accumulation’ when referring to the ‘nyenpa’.