Who is Viola?
Identity
"Conceal me what I am, and be my aid
For such disguise as haply shall become
The form of my intent. I’ll serve this duke.
Thou shall present me as an eunuch to him." (Act I Scene II 50) This quote means she was completely on board with becoming a guy and serving the duke.
Gender
And might not be delivered to the world,
Till I had made mine own occasion mellow,
What my estate is." (Act I Scene II 40) This quote means she needs to be anything but a women. She needs a job and somewhere to stay.
Perception
I left no ring with her. What means this lady?
Fortune forbid my outside have not charmed her!
She made good view of me, indeed so much
That sure methought her eyes had lost her tongue,
For she did speak in starts distractedly." (Act II Scene II 15) Olivia even fell in love with her.
This quote means Viola realized Olivia fell in love with her, because she thinks she is a guy.