"The girl is Mexican."
Translation:La niña es mexicana.
When a baby is born and it is female, they would never call it a CHICA. IT would be a NIÑA. ( or if it is a male, the baby is a NIÑO and not a CHICO. For some people in Mexico, the word CHICA is not very dignified (nor is the word CHICO). At about 14 years old, in Mexico, the niña becomes a muchacha, but when you are talking formally to that person you should refer to her as a señorita and not a muchacha in order to show respect (and if it is male, the muchacho should be referred to as joven to show respect. Don`t know about the other 20-some countries where they also speak Spanish.
The first syllable of "ME xico" is stressed, so it needs an accent on the E, because according to the rules of Spanish the stress for a word with these letters would normally be on the second-to-the-last syllable. For example, the city of Tampico is stressed on the letter I. (tam PI co). When the word ends in a vowel (a,e,i,o,u) or when it ends in S or N then the stress is on the second-to-the-last syllable. Many place names have the stress on a different syllable, so then you have to write in the accent: Perú, Yucatán, Mérida, Michoacán.