You would multiply the lengths to get the area of each side of the prism.
1st side: 5m x 6m = 30m squared
2nd: 5m x 6m = 30m squared
3rd: 5m x 4m = 20m squared
4th: 5m x 4m = 20m squared
5th: 4m x 6m = 24m squared
6th: 4m x 6m = 24m squared
Then you would add them all together.
30m squared + 30m squared + 20m squared + 20m squared + 24m squared + 24m squared = 148m squared