Well, there are 5 players on each team.
Team A: 5 players (A,B,C,D,E)
Team B: 5 players ( 1,2,3,4,5)
A gave high five to 1,2,3,4,5
B gave high five to 1,2,3,4,5
C gave high five to 1,2,3,4,5
D gave high five to 1,2,3,4,5
E gave high five to 1,2,3,4,5
(It would be the same for the other team)
So all together, there would be an exchange of 25 high fives.