What is the functionality of UBound in for loop for the below code.
x = wsPlan.Range("A1").CurrentRegion.Value
Set Plan = CreateObject("Scripting.Dictionary")
For i = 3 To UBound(x, 1)
For j = 2 To UBound(x, 2)
Plan.Item(x(1, j) & x(2, j) & x(i, 1)) = x(i, j)
Next j
Next i