Does tripel mean it’s triple octane?
In a sense, yes, if by octane you mean malt. According to the Oxford Companion to Beer, “the term ‘tripel’ refers to the amount of malt with fermentable sugars and the original gravity.” One interesting theory is that barrels of tripel were marked "XXX" using the medieval system of using X’s to mark the strength of a beer back when this was something the monks were making with all their free time. (Obviously, this means dubbels would’ve been marked "XX" with their lower alcohol content.)
Sort of confusingly, dubbels are darker than tripels, with ABVs usually ranging from 6 to 7.5%. Tripels are much lighter in color but higher in alcohol, around 7.5 to 9.5% (and sneakily higher in alcohol, at that, as they have a nice dry finish).
If I don’t know what I want, how do I even figure it out?
This is the best part about beer: you get to go out and you get to try a ton of stuff! If you’re confused, ask your bartender or beer merchant. Get a feel for what you love and what you hate. It’s no different than food, wine, spirits, music, movies, preferred thermostat temperatures, or which side of the bed you sleep on. Everyone is different and likes different things, and you should never apologize for what makes you happy.