Question about GUAPA
 

I learned that guapo means handsome, but yesterday I heard someone call a woman guapa, which sounds weird because I wouldn't call a woman handsome. Is this usage right? Is it common to use the word guapa with women instead of hermosa or bonita? Thank you.

Guapa it's a VERY common compliment for women, girls and babies (femenine, of course). Means pretty, elegant, and so on.
It's commoner as hermosa or bonita, and has the same meaning.

Usually bonita and guapa are more for everyday use (girls, babies, women). Hermosa it's more for woman a party/night dress, writing language and things like landscapes and pretty things. But every woman loves this kind of words, and they overlook your possible bad usage.

Examples of use of guapa: :D (Same usage with bonita/hermosa)
Babys: "tu niña ha crecido mucho y está muy guapa"
girls:"Con ese vestido estás muy guapa"
man to woman: ¡¡GUAPA!! You must make it short and loud, looking from face to toe and return. Other option it's slower with a little roaring guapa + grrrrrr :cool:

Saludos:D

Quizás es más común en España, porque solemos usar menos el "linda"....
GUAPA es para mujeres, pero se oye mucho para otras cosas.
Incluso se ha deformado un poco, y se oyen cosas como "este coche está guapo" (para un coche tuneado) ó "Se metió en un lío guapo guapo" (para decir que se metió en un gran lío)

Saludos :D

I don't necessarily understand all the nuances of the Spanish language, but for what it's worth, I have heard guapa used in reference to both women and girls of all ages to mean pretty, dressed up, nice looking etc.