Encapsulation type : Ethernet (1)

It's a Wireshark-internal value that represents the particular link-layer header type for the packet in question - and the numerical values are subject to change from release to release, so perhaps we shouldn't be displaying it.

Wireshark's capture-file-reading code maps the link-layer header type or types in the file - which have values that may be different for different file types - into the internal value so that the Wireshark dissection code doesn't need to know the particular values used in pcap/pcapng files or the ones used in Microsoft Network Monitor files or the ones used in {Ether,Token,Airo,Omini}Peek files or....