This is the 802nd most frequent Chinese word.
讲话
To speak or talk.
In this sentence, '讲话' refers to the action of speaking, particularly in a formal context such as a meeting.
他在开会时喜欢讲话。
He likes to speak during meetings.
Here, '讲话' is being used to denote speaking or lecturing by a teacher in an educational setting.
老师在课堂上讲话时，请不要打扰。
Please do not disturb when the teacher is speaking in the class.
In this context, '讲话' is used to refer to giving a formal speech or address.