Hi Prakash,
1. Create a visual with all countries and sales.
2. Sort the country with sales.
3. Select the countries values from the visual and click on group icon which is shown in the tooltip while selecting multiple values from the visual.
4. Right click on the created group and click Edit group.
5. Tick on 'Include Other'.
6. Click ok.
7. You can see 2 groups with other and top countries group.