By this sentence, the queen meant that she can see only what is real.
We can arrive at this answer because:
This scene puts Hamlet's mental rationality in doubt. The queen begins to suspect that her son is crazy and that is why she says the sentence shown in the question above, where she means that she can see everything that is real, but spirits and other silly things, she cannot see.
More information about "Hamlet" at the link:
https://brainly.com/question/8182660