This property is used to define any groups to be applied to the grid. The example below groups items by Status. The property should contain a root node value of Groups. The root node Groups should contain child node value Group, which will represent each grouping you want to set up in the grid.
<groups>
<group>
<FieldType>Group</FieldType>
<FieldName>Status</FieldName>
</group>
<group>
<FieldType>Select</FieldType>
<FieldName>Status</FieldName>
<FieldAlias>Status</FieldAlias>
<HeaderText>Status</HeaderText>
</group>
</groups>