It doesn't "equal wants", in exactly the same way that "at the" doesn't "equal have".
Bí ó is a phrasal verb that can be used to say "want" or "need", in much the same way that the "phrasal verb" bí ag can bé used to say "have".
Tá X ag Y - "Y has X"
Tá X ó Y - "Y wants/needs X*
As SatharnPHL suggests in https://forum.duolingo.com/comment/9454774$comment_id=34447344, it is similar to the way tá ... ag ... means to have. If something is "at you", you have it; if it is "from you", you want it.
I'd just like to make it clear that I have never said "If something is "at you", you have it; if it is "from you", you want it".
Irish speakers don't perceive the ag in tá rud agam as meaning "at", any more than English speakers think the "have" in "I have to go now" has anything to do with possession, or the "on" in "on fire" indicates that you are physically positioned on some fire, etc.
Tá X ó Y is structurally similar to Tá X ag Y, and if you have gotten used to the fact that Tá X ag Y means "Y has X", then Tá X ó Y shouldn't pose too many challenges.