Maybe. It depends entirely on the context in which this is used. Can you tell us more? (Aside from the fact that forum rules don't just request context, but require it, it is impossible to answer this question without it.)
The authorities of a school give someone a certificate confirming he/she is the best master student based on some accomplishments; now if we want to mention it in the resume are the words in parentheses needed?
If this is an elementary or secondary school, not a university, then it is important to be careful about "master student," since a person at a university studying for a master's degree (a degree whose full title begins with the words "Master of") is a master's student. "Master student" could easily be mistaken for an error for "master's student."
For that reason, I wouldn't use the term "master student" at all, as a school administrator or as a resume writer. Even if the Spanish term could be translated literally as "master student," I would use a different term in English. If the "best master student" is the one student with the highest grade in a course, or the highest average grade in a group of courses or over a period of years, then I would strongly suggest describing the person as the "highest-scoring student" or "most distinguished student" or something else.
If the "best master student" has the highest grade average over an entire secondary school curriculum, we have a special word in American English (I don't know if it is used in other Englishes) for him or her: valedictorian.
Well, a student in a university program that grants a degree that includes the words (in English) "Master of" is a master's student in a master's program. That possessive—the apostrophe and letter "s"—is very important here, at least for the U.S.
But in the U.S., at least, a university student who already has a bachelor's or baccalaureate degree (a degree whose full title includes the words "Bachelor of") degree, earns a master's degree by completing a specified set of courses, and perhaps writing a master's thesis (there are "non-thesis" master's degrees in the U.S.). A student who has earned a master's degree is awarded a diploma. A U.S. unviersity does not "give someone a certificate confirming he/she is the best master student based on some accomplishments."
If you are talking about one student among several in a master's program being given a special award for being the "best" or top student within a "class" in a master's program (all the students who are going to receive their master's degrees at the same time), then I think there is going to have to be more explanation, at least for anyone in the U.S., such as a potential employer, who might read the resume.
"The best masters student" would not be quite correct—it would have to be "the best master's student." On a resume using a "headline" or "telegraphic" style, the article could be omitted, but the apostrophe and s are not optional.