Understanding Uniform Grid control

UniformGrid contains two properties, Rows and Columns, for setting the number of rows and columns. Controls are added to the grid in the order that they are declared. So there will not be any column in between them. In your example you have declared Columns=3 and you have added only two controls. But if you add another control it will place in the end.

  <UniformGrid Name="uniformGrid1"
                 Rows="2"
                 Columns="3">
        <Button Content="Rohit"
                 Margin="2" />
        <Button Content="asit"
                 Margin="2" />
        <Button Content="asit"
                Margin="2" />
    </UniformGrid>

As shown in the MSDN article for a UniformGrid, there is no Grid.Row or Grid.Column attached property.

Instead, Intellisense may be suggesting it because you have a Grid further up the document tree. If it were an attached property, it would be far more likely to be called UniformGrid.Row as that is how attached properties are accessed.