There are, of course, requirements to fulfill when someone applies for a visa to come to another country, so are there when it comes to applying for UK visa. One of the requirements for UK visa is adequate English skills. Thus, anyone who wants to come to the UK needs to prove that they have the skills required. How? Here are some of the ways one can prove his English skills:
First, you can take an English test to prove the skills. At least, your skills have to be on the level of B1, B2, C1 or C2. Basically, this level means you have at least medium skills. For example, if one applies for naturalization or spouse visa, then he or she needs to take an english test for citizenship.
The best way to prove that you have sufficient skills in English is to come from an English-speaking country like the United States, Australia, Canada or New Zealand. If you come from one of these countries, you do not really need to prove your skills.