To become an independent country means to gain sovereignty and become a separate political entity, free from the control or influence of another country. Full definition
Like siblings with different personalities, the three former French colonies in North Africa — Morocco, Algeria and Tunisia — have developed very differently since becoming independent countries in the 1950s and 1960s. (africanlawbusiness.com)
Everybody knows I desperately want to see Scotland become an independent country, but the decision on that will always lie where it firmly belongs, and that is in the hands of the Scottish people. (itv.com)
The UK Government stated that, if a simple majority of the votes cast were in favour of independence, then «Scotland would become an independent country after a process of negotiations». (en.wikipedia.org)