The NIV translates it, "...the one who is wise saves lives."
What does it mean to save a life or win a soul? Does it mean that you've added a member to your church? Does it mean that you've helped someone avoid death?
I think you know the answer. But why is it wise to win souls, to save lives? Do we get rewarded?
To win a soul over to Jesus and in effect save them from their own destruction is wise because it is part of our calling to make disciples. We are to fill the earth with God's glory and as the Word of God germinates within us, we must allow our roots to take hold in good soil and spread accordingly.
To save a life is to win them over to Jesus. To win them over to Jesus you must be His disciple. To be His disciple you must take up your cross daily. Inch my inch, you have to live the Gospel.