I suppose it would be mostly practical skills, cooking, fixing things. Usually had to be done by people themselves.
Maybe also mental things like navigating (with or without paper map) and remembering their daily and weekly agendas.
What other things would be a big difference with the people today?
Eh even before the Internet people had other tools to help with this. Physical books with people’s addresses and phone numbers. Specialized holders for various business cards. Yellow pages and white pages. I suppose a lot of incidental memorization is lost but I don’t think it’s really a skill lost so much as the tool changed.
And those tools pre-date the invention of the telephone, so it’s not like people spent hundreds of years memorizing phone numbers before writing was invented.