Something obvious is plain to see and easily understandable. It was obvious that you didn't enjoy your meal because I found it rolled in a napkin and shoved under the rug.
There's nothing vague about the adjective obvious — it's right there in front of your eyes! It describes something that's easy to figure out or the most straightforward option. If someone states the obvious, you're likely to respond with a sarcastic "No duh!" or "Thanks Sherlock." If obvious isn't the obvious word of choice, you can try a synonym such as "evident" or "apparent."