Those are algebra tiles, so it is saying (if you read across the top) 2x +2 then if you read down you have 3 units, so the dot means 2x + 2 multiplied by 3
If you write it in algebraic terms it is 3(2x+2) so the answer when you distribute is 3 (2x) + 3(2) so 6x + 6, and if you count the number of red rectangles you have 6 of them, hence the 6x, and if you cound the units in gray you have 6 of them, hence the 6.
Algebra tiles are used to demonstrate algebra concepts
