Complex sentence: General American (commonly abbreviated as GA or GenAm) is a major accent of American English, particularly considered the American accent that is the most neutral, or the most lacking in distinctive regional, ethnic, or socioeconomic characteristics.
Split into simpler sentences: General American (commonly abbreviated as GA or GenAm) is a major accent of American English, particularly considered the American accent that is the most neutral. In other words, the most lacking in distinctive regional, ethnic, or socioeconomic characteristics.