The document discusses the simple future tense in English, which can be expressed using "will" or "be going to." While these forms can sometimes be used interchangeably, they often convey different meanings. "Will" typically suggests a voluntary action or promise, while "be going to" implies something planned or scheduled. Both can also be used to make general predictions about events outside of one's control. The document provides examples of affirmative, negative, and interrogative sentences using "will" as well as situations when "will" expresses voluntary actions, promises, and predictions.