Very new to R, need help in merging

I have a dataset with 74 countries in one column and 74 (repeated) regions in next column. There are 4 levels for regions.
I need to make a table of the number of countries per region. The regions should be listed in decreasing order of the number of countries.
Next thing to do is:
Identify the regions where less than 10 countries are reported. In what follows, we will
not calculate the regional statistics for these countries, nor will we show their graphs.
Similarly, we will not take the countries into account whose region is missing.

*File attached

Please help me to solve this... Thanks in advance