Final answer:
A sebaceous gland is the type of gland that secretes oil for the skin and hair, generating a substance called sebum which has moisturizing and antibacterial properties.
Step-by-step explanation:
The type of gland that secretes oil for the skin and hair is known as a sebaceous gland. These glands are exocrine glands found all over the body and are most commonly associated with hair follicles. They produce and release a substance called sebum, which is a mixture of lipids that lubricates and waterproofs the skin and hair, keeping them pliable and protected from drying out. The antibacterial properties of sebum also inhibit the growth of microorganisms on the skin.