Speaker's pauses are an important part of public speaking. UMS stands for 'Umms and Ahhs' which are the filler words that speakers use to fill in gaps in their speech. ERS stands for 'Errors and Repetitions' which are mistakes that speakers make while speaking, such as repeating words or phrases. Both UMS and ERS are common occurrences in public speaking and can be used to indicate a speaker's pauses.