several long cylindrical objects
Used for counting a few long, thin items such as bottles, pens, trees, or rolled objects. The exact number is vague but typically 2–5.
See also: 本 (ほん)
There are several pens on the desk.
Several cherry trees are planted in the park.
数本 is used for a few long, cylindrical objects like bottles or pencils, while 数個 is used for general countable objects.
Compound of 数 (several) + 本 (counter for long cylindrical objects). The reading すうほん follows standard on'yomi.