what is meant by valid GATE score

Hello Aspirant!
A valid score in any exam means a score above the minimum marks required in that particular exam to get admission in an institution.
Just like you need marks more than the passing marks to qualify in school exams, a valid GATE score may refer to any score above the least score requirement to fulfill the eligibility criteria for admission usually in a PG technical College/University.

And yes, remember that your GATE score is valid (acceptable) only for 3 years from the year in which you have appeared in the exam.

Don't hesitate to ask your doubts in the comment section.
Hope this answer will be helpful to you.

A valid GATE score is something that you need to score above the score for qualifying. For example, if the qualifying GATE score is 20 and you score 21, it is called a valid GATE score. But if you score 15, then it is not a valid GATE score.