Coherence is best described as
the unity in a paragraph
the conclusive repetition in body paragraphs
the order of ideas enabling the reader to move easily from point to point.
the development of a major thesis

Coherence is best described as the order of ideas, enabling the reader to move easily from point to point. It is coherent when the words, phrases and sentences used are related, logical and supports the idea of the each line. The ideas are interconnected which would make the article or the paragraph smooth flowing and easily understood by the readers. 

Acquiring english is a way of learning where you learn english by birth, this includes listening to your parents, brothers and sisters and on the whole learning it from the environment around you while mastering standard english need qualified institutes and teachers who make certain programs and syllabus to you master the standard english. this also can include a long session of academic studies before you can master the standard english.standard english is necessary for literary works, official usage and writing materials for standardized publications or when someone needs to speak publicly. in most cases the employers of a company also demand and like the use of standard english from their employees.