Demonstrative adjective: It modifies the noun, science lab, and indicates which one is being referred to. Deictic word: It points to a specific, nearby location or object, implying proximity or immediacy. In this context, this means, the one we're currently talking about or referring to and the one that's nearby or present. The English significance of the word this, is that it helps to clarify which noun is being referred to and provides spatial or contextual information can be used to contrast with other nouns (e.g. this vs that). In the sentence, "this" points to the amazing science lab that the speaker is excited about, implying that it's a notable or impressive facility, much like a mini NASA. I trust that this explanation will help you.