The first column has 10 cubes.
The question states that the other two columns each have 4 fewer cubes than the first column.
10 - 4 = 6
This means that each of the other 2 columns have 6 cubes each.
Column 1: 10 Cubic units
Column 2: 6 Cubic units
Column 3: 6 Cubic units
10 + 6 + 6 = 22
Anna’s Figure has 22 Cubic Units