Broadcast Frame is a frame that has a hexadecimal MAC address of FF-FF-FF-FF-FF-FF indicating that is intended to be received and processed by every node on the network.
What is Broadcast Frame (in computer networking)?
In Ethernet networks, Broadcast Frame is a frame that has a hexadecimal MAC address of FF-FF-FF-FF-FF-FF. This hexadecimal address is equivalent to 48 binary «ones». The meaning of this address in Ethernet is simply that this frame is intended to be received and processed by every node on the network of computers.
Broadcast frames are generated when certain network services need to make announcements to other hosts on the network. Too many broadcast frames on a network can degrade communication between nodes on the network.

Note:
Most routers are not configured to forward broadcast frames to other subnets in an internetwork; therefore, broadcast frames used as announcements are limited in scope to the local subnet on which the broadcasting host is located.