A pentagon has 5 sides, 12 pentagons have 60 sides.
A hexagon has 6 sides, 20 hexagons have 120 sides.
In total, there are 120 + 60 = 180 sides.
However, if you look (or imagine) at any ball, you can see that each side is touching two faces. This means that every 2 sides in those 180 sides join together to form one seam.
So, there are 180/2 = 90 seams.
Just for fun, a soccer ball is a truncated icosahedron. You can easily verify online that it has 90 edges.