Students are very important. Not only are they our future, but they have a great impact now. I know many students who have done great things. I know students who have started recycling campaigns, energy use and awareness campaigns, deforestation campaigns, etc. This is very good for molding the future because they are bringing awareness out in to the open.
Students can play a vital role in moulding the future. The idea that students can understand content and then take that understanding to help develop their own impressions in the future is a powerful element in education. This can have both positive and negative realities within it. The believe that drives many in education is the idea that students can gain skills through content, ideas through empowerment, and then be able to apply said skill set to the future in the hopes of making things "different and better." This is a very optimistic element within teaching, and perhaps the source of its greatest strength and simultaneously its greatest weakness. Students, like all human beings, have the capacity to alter the landscape of the future and the motivating force behind many teachers is to be able to powerfully impact the lives of their students so that this becomes a reality.
If you're using the term "students" to refer to young people in general, then they mold the future simply because they *are* the future. When their generation grows up, they will be the leaders, voters, business owners etc and therefore they will mold the future.
If you're using the term "students" to mean those who attend school (and eventually university), the idea is more or less the same. But in this case, you can reasonably expect students to become more "important" in shaping the future because they are likely to occupy positions of greater responsibility.
The statement in the question can be interpreted to mean two things. One is that students are doing something today or now that will impact the future in a big way. The second interpretation is that in future when students grow up, they will be in the most active and influential age group in the society, they will have major impact on the kind of society that exist at that time.
If we accept the first interpretation, I believe that the statement is not very correct. If we accept the second interpretation, the interpretation itself explains how student will pay an important role in moulding the future.
This statement is generally made to point out to the younger people the responsibility they will need to shoulder in the future and the importance of such responsibility. The purpose of doing so is to motivate them to make efforts now to prepare themselves for the responsibilities that awaits them in future.