"You like cake."
Translation:Vi ŝatas kukon.
Maybe for the when people say "I am like you", in which "like" is used as an adjective, but of course the "you" in the sentence would have to be a plural noun for "kia" to have the -j ending.
When do you use -on and when do you use -o? Please explain it simple as possible.
Use -o when a noun is after the verb esti or after a preposition and use -on when a verb is acting upon the noun.