What is BitPay and how does it work?

Could you please elaborate on BitPay? I'm curious to know what it is and how it functions in the cryptocurrency world. Is it a payment processor that facilitates transactions using Bitcoin and other digital currencies? If so, how does it ensure secure and efficient transactions for both buyers and sellers? Additionally, are there any specific benefits or advantages that make BitPay a preferred choice for merchants looking to accept digital payments? I'm eager to learn more about this topic.