Base 10 blocks are in sets of 1s, 10s or 100s. In base 10 each group represents a specific number. They are also represented by dots for ones, lines for 10s and squares for 100s.

These are other frames. You can also use other frames in different bases. For example in base 6 you use a 6 frame; in base 4 you use a 4 frame. 

To Build and Show Addition you use the number blocks to represent each part of the problem. For example 542 + 54 would be 5 squares, 4 longs and 2 units and then add on 5 longs and 4 units. Now put them together for 5 squares, 9 longs and 6 units for an answer of 592.