If I take Spanish lessons here in the U.S. will it help me? I've heard that it won't because of the different dialects.

I know its a bit different from spanish, but a spanish person can understand a portuguese person, but with their different dialects etc. can a mexican?

I'm beginning to think my friends made it up. Please help, this word is plaguing me.
I don't mean to be offensive by saying Mexican Spanish. It's just that my Columbian, Puerto Rican, Peruvian, and Spanish friends have never heard the word, but it was explained to me as a word used in Mexico. Different countries have different dialects, ya know. I am doing my best to be culturally sensitive, not offensive...so relajate dyani

I'm thinking about going to Chile to teach English over the summer, but I heard different dialects of Spanish can be hard to understand. I think the Spanish I learned in high school is Mexican Spanish.