兵士たちは遮蔽物の後ろに隠れた。
The soldiers hid behind cover.
This wall serves as a shield against sunlight.
隠れ場 is a hiding place in general, while 遮蔽物 specifically implies an object that physically blocks or shields.
Compound of 遮蔽 (shielding) + 物 (thing). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for technical terms.