Translation:He is going to live in Mexico for a year.
This is from a language site called "Stackexchange": I think that the simplest explanation it that "por" means that something has happened during all the extension of the time period mentioned, whereas "durante" points to some occasions during that period:
Durante febrero, las condiciones empeoraron: At some point in February, the conditions got worse, but not necessarily continuously... perhaps the rest of the month was OK but on the 20th they really got worse. Durante dos años trabajé allí ocasionalmente: I worked there as a temp, on and off.] Trabajé allí por dos años: every day, 9 to 5. Durante años los científicos pensaron esto: they thought that, but only on the occasions when they gave some attention to the matter. Por años los científicos pensaron esto: they thought it continuously, with no change of opinion.
That been said, there is still a restriction that "por" needs to be used with indeterminate periods (never mind plural/singular): por años por tres años por cinco horas pero nunca por el miércoles, por 1980 (could be used but in the sense of "around 1980"). Durante can be used in all of those cases: durante años, durante 1980.