oscillating fan
A fan whose head rotates from side to side to distribute air over a wider area. Common in homes and offices.
It was hot, so I turned on the oscillating fan.
扇風機 is a general electric fan; 首振り扇風機 specifically refers to one with an oscillating function.
Compound of 首振り (neck-swinging, oscillating) + 扇風機 (electric fan).