define english non-lexical fillers and thier usuage?

Answer 1

A non lexical filler is an extra "word" that is added.
eg. a)we went to the cinema last night and saw a good film

b)we,er,went to the, em, cinema, er ,last night and, uh, saw a good film.

The 'er,em and uh' in sentence b) are non-lexical fillers,they have no real meaning of a word and are used maybe for thinking time.

In answering a question with "yeh,mm or ah" it indicates that the person hasn't anything to say and are happy to listen.

Hope this is clear enough.

Answer 2

those words which comes meaninglessly in case of verbal communication, for example, hhhhh, shhhhhh, hmmmm.