Answer:
There are three demonstrative adjectives in Spanish. I will be using the masculine versions for now:
1. Este meaning this - something that's close to you.
2. Ese meaning that - something's that still fairly close to you but not that far away.
3. Aquel meaning that - Aquel and ese are quite similar, but aquel means it's pretty far away.
How the demonstrative adjective changes based on the subject:
Masculine singular: Este, Ese, Aquel
Feminine singular: Esta, Esa, Aquella
Masculine plural: Estos, Esos, Aquellos
Feminine plural: Estas, Esas, Aquellas
Example sentences:
Este profesor habla mucho = This teacher talks a lot
Esa camisa es bonita = That shirt (you’re wearing) is pretty
Aquellos estudiantes no comprenden = Those students (over there) don’t understand
Esta chica está lista = This girl is ready
Esos libros son estúpidos = Those books (you just picked up) are stupid
Me gusta aquella casa = I like that house (on the other side of the street)