Subject + 伸出 + Body Part
伸出 (shēnchū) means "to stretch out" or "to extend." It describes the action of reaching out a body part, most commonly a hand, as in 伸出手 (to stretch out one's hand).
他伸出手来帮我拿行李。
Tā shēnchū shǒu lái bāng wǒ ná xíngli.
He reached out his hand to help me with my luggage.
小猫从窝里伸出了一只爪子。
Xiǎo māo cóng wō lǐ shēnchūle yī zhī zhǎozi.
The kitten stretched out a paw from its bed.
她从车窗伸出手向我们挥手告别。
Tā cóng chēchuāng shēnchū shǒu xiàng wǒmen huīshǒu gàobié.
She reached her hand out of the car window and waved goodbye to us.