प्रवृत्तिं च निवृत्तिं च कार्याकार्ये भयाभये।बन्धं मोक्षं च या वेत्ति बुद्धिः सा पार्थ सात्त्विकी॥
pravṛttiṃ ca nivṛttiṃ ca kāryākārye bhayābhayebandhaṃ mokṣaṃ ca yā vetti buddhiḥ sā pārtha sāttvikī
Word by word
The verse says
The understanding that knows when to act and when to hold back, what should be done and what should not, what to fear and what not to fear, what binds and what frees: that one, Arjuna, is clear.
In plain words
The best understanding, described by four pairs.
When to go and when to stop. What to do and what not to. What to be afraid of and what not to be. What ties you down and what lets you go.
And look at the third pair. Knowing what to fear is listed as part of good judgement, which is not how we usually talk about fear.
Where you've felt this · at work
A site foreman walks a half-built floor and is entirely relaxed about the scaffolding, which looks alarming to you and is fine. He then stops everything over a damp patch on a wall that you had not noticed. He is not braver or more anxious than you. He knows which of the two can kill someone.
Going deeper
Fear being treated as a judgement rather than a feeling is the most useful idea in this verse.
We talk about fear as something you have more or less of, as though the goal were to reduce the quantity. Here it is a matter of aim. Good understanding is not fearless; it is afraid of the right things and not afraid of the wrong ones.
That reframing helps because the quantity approach fails. Telling yourself not to be afraid of something you find frightening almost never works. Asking whether this particular thing can actually hurt you, and what can, is a question you can make progress on.
Most people's fear is badly aimed rather than excessive. There is a great deal of worry pointed at being embarrassed and very little pointed at spending thirty years doing something that does not matter to you.