1.
hands and feet, limbs
The hands and feet collectively, or all four limbs of a person or animal.
2.
right-hand man, trusted agent
A person who acts as an extension of someone else's will, carrying out their orders faithfully. Often used for subordinates or loyal followers.
Usage
In sense 1, 手足 refers to the physical hands and feet (or all four limbs). It is commonly used when describing sensations like cold or numbness, or physical movements.
In sense 2, the word is used figuratively to mean a person who faithfully carries out someone else's wishes, like a loyal subordinate or agent. The expression 手足のように使う ("to use someone like one's own hands and feet") can carry a negative nuance of treating people as mere tools.