Hi and thanks for asking.

When a girl becomes aroused (turned on), the clitoris does become erect. While the clitoris is much smaller than a penis, it is made up from the same erectile tissue as a penis.

When stimulated, this tissue fills with blood and has similar nerve endings which give pleasurable feelings. When the clitoris is stimulated it may be more sensitive to touch, look redder and stick out past the labia. These changes may be more noticeable in some girls than others.

Hope this helps.