"This" is a demonstrative pronoun. Demonstrative pronouns are pronouns that point to specific things. "This, that, these, those, none and neither" are Demonstrative Pronouns that substitute nouns when the nouns they replace can be understood from the context. At the same time, to indicate whether they are close or far, in space or time, from the speaker in the moment of speaking. They also indicate whether they are replacing singular or plural words.
"This" (singular) and "These" (plural) refer to an object or person NEAR the speaker.
"That" (singular) and "Those" (plural) refer to an object or person further AWAY