The address 255.255.255.255 is a special address used to send a broadcast message to all PCs on the local network (192.168.2.X). Port 67 is one of several ports used for DHCP - this is the process that automatically assigns IP addresses to PCs on a network. On a home network, it is very common for your router to act as the DHCP server and assign addresses to all PCs that attempt to connect to it.
In the examples you've qouted below, you should accept and remember these two alerts.
The first one allows the executable svchost.exe (Services Host - a critical Windows file) on your PC to check the connection to your gateway (ths is the ICMP packet).
The second one allows svchost.exe on your PC to send a broadcast UDP message across the LAN (using the special address 255.255.255.255) to port 67, requesting an IP address to be issued to it. When your router receives this request, it will allocate the next available address to the PC requesting it.
Hope this helps,