You have highlighted one of the aspects of this play that characterises it as an excellent example of the Theatre of the Absurd. What is clear about this play is that in it Beckett deliberately seeks to create and present us with a chaotic world that seeks to undermine our basic security in certain given facts about life. One of those facts is the precise nature of language, or its ability to communicate meaning in a specific way. Consider the following quote:
Do you want a carrot?
Is that all there is?
I might have some turnips.
Give me a carrot. (Vladimir rummages in his pockets, takes out a turnip and gives it to Estragon who takes a bite out of it. Angrily.) It's a turnip!
Oh pardon! I could have sworn it was a carrot.
There is an element of humour in this exchange, but also at the same time we are made to doubt the ability of words to capture the description and identity of something. What, at the end of the day is the word "carrot"? What meaning do we attach to it? Why could the word "carrot" not refer to a turnip? Such examples in the play profoundly challenge the basis of our communication and suggest that words are just labels that we have attached to various objects and could as a result be just as easily reattached. Language, just like so many other things in this play, becomes difficult to pin down.