Some UK visas require language, while others do not.
Visitors and, refugees have no language requirement.
Visa types such as working/investing such as Tier 5 Temporary Worker, Tier 5 Youth Mobility Scheme, UK Ancestry and Tier 1 Investor are also not required. In addition, Adult Dependent Relative, known as a family visa, does not require a language requirement.
Usually people under the age of 18 and over 64 do not have an English language requirement.
But there is a certain language requirement for work visas, family visas and education visas. English proficiency is also required for settlement applications.
English must be met in different forms. The simplest way is to become a citizen of an English-speaking country, published by the Ministry of the interior, or to become a citizen of Malta.
A second way is to have an English language diploma. A different level is expected for each visa. Taking an appropriate exam at the Famework of Reference for Languages (CEFR) level is important as your grade, or your exam will be ignored and your application will be rejected.