"I like a boy."
Translation:Jag tycker om en pojke.
Ok so, I red lately about this and got that explaination; In sweden there is actually 3 genders, masculine and feminine who are combined as "relative gender" (not sure if it's the right word) but in sweden you use "en" and for "neutral gender" such as objects or concepts you would use "ett". Hope its clear enough
even though your thinking is logical, "tycker om" is a fixed expression meaning "like". It's like "spilling the beans" in English (meaning "revealing secret information"), where the meaning lost the connection with the actual words in that specific expression and it has nothing to do with the legume seeds anymore