What is the difference between the demonstrative pronouns "Ese" and "Eso". They both seem to be singular and masculine.
I am looking a demonstrative pronouns. My text book throws in "Eso" without explaining how it is different from "Ese".
3 Answers
Ese (or ése if it's ambiguous) means 'that' and is the masculine singular demonstrative pronoun.
Eso also means 'that' but is the neuter singular demonstrative pronoun so is used for ideas etc anything without gender:
Eg: Tengo que salir a las tres. No olvida eso. 
Ese - used for masculine nouns, and when the noun is also in the sentence. Ese niño juega.
Eso - used when there is no noun in the sentence, simply that. Eso es bueno.
The same applies to esto and este.
However, only esos and estos are valid plural formations. Estes and eses do not exist.
"Ese/esa*" also means "that one":
Ese (coche, sombrero, etc.) es el mejor = That one (masculine) is the best Me gusta esa (manzana, chancla, etc.) = I like that one (feminine) Here's a more difficult one:
Este (día) es un nuevo día = This (day) is a new day
The confusing thing is that we translate "este" as "this" instead of "this one". The reason for this is that the question isn't whether it's a day; it's about what kind of day it is. We don't say "This one/day is a new day" in English because it's repetitive, but in Spanish, simply changing the "o" to an "e" adds no repetitiveness.
*Some people may write this as "ése/ésa" (éste/ésta) since that was what was considered correct by the RAE before, but now the RAE says the accent is not required.
Use eso when referring to an abstract idea.
