It's possible that you've misheard or misunderstood a phrase, or that it's a regional or informal expression.
Here are a few possibilities you might be thinking of:
* "Be onto something": This means to be on the right track, to have a good idea, or to be close to discovering something important.
* "Be up to something": This means to be doing something sneaky or suspicious, or to be involved in something that's not quite right.
* "Be on the ball": This means to be alert, attentive, and ready to act.
* "Be self-aware": This means to be conscious of your own thoughts, feelings, and actions, and how they affect others.
If you could provide more context about where you heard this phrase, I might be able to help you understand what it means.