This is the 3487th most frequent Japanese word.
神経
"Nerve."
In this sentence, "神経" (shinkei) is utilized within "神経質" (shinkei-shitsu), which means "nervous" or "sensitive" in describing a person's mental state.
私は神経質になりやすいです。
I tend to become nervous easily.
Here, "神経" explicitly refers to the physical nerves in the human body.
医師は神経損傷を診断しました。
The doctor diagnosed nerve damage.
In this context, "神経" is used metaphorically to indicate annoyance or irritation, as in touching someone's sensitivity.