What does it mean if a girl looks at you a lot when you aren't looking?

So I have a good crush on this girl at my work, and I have liked her since November and it seems she likes me too, but I don't necessarily know for sure, but I want to ask this, so she has been looking at me a lot when I am not looking, and whenever I catch her she instantly looks away, what could this mean?
What does it mean if a girl looks at you a lot when you aren't looking?
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