What is difference between esto, esta and este?
Esto is impersonal and masculine (i know, it's kind of tricky) the fact is that things have a gender as well.
Esta could be a person or a thing and it's feminine, same as este but masculine.
Este means east as well.
este- adjective for something masculine; ex: este libro (this book)
esta- adjective for something feminine; ex: esta manzana (this apple)
esto- adjective for something "neutral" (unknown gender)
These are not to be confused with ésta, ésto and éste
éste- masculine noun; ex: Quiero éste. (I want this one.); "this one" can refer to a pencil, for example (el lápiz)
ésta- feminine noun; ex: Quiero ésta. (I want this one.); "this one" can refer to a plant, for example (la planta)
ésto- neutral noun (unknown gender); ex: ¿Qué es ésto? (What is this?); the object is unknown.
What is the difference between esto,esta and este?
These are all used as demonstrative pronouns not adjectives
(According to The Real Academia Española the written accent may be omitted where there is no confusion with the (demonstrative) adjective: esta )
ésto (neutral or masc) por ejemplo: ésto es lo más dificl = this one is the most difficult
(the object represented by this** is not specified / known so the neutral form is used)
éste (masc + sing) = this one
éstes (masc + pl) = these ones
por ejemplo: éste es el mio = this (one) is mine
un día de éstos = one of these days
ésta (fem + sing) = ¡ Qué niña ésta ! = Honestly, this child ! / Oh, this child !
este (without accent) = east
As demonstrative pronouns, este is masculine , esta is feminine, and esto is neuter. The first two are fairly clear, since they always refer to nouns with matching gender. However, unlike many other languages, Spanish has no nouns with neuter gender. However, expressed ideas, speech, and unidentified or unknown objects are all referred to using neuter pronouns. In these situations the grammatical element (not a noun) to which the pronoun refers is either neuter or its gender is unknown to the speaker.
Neuter pronouns are sometimes used to refer to objects with a defined gender, however this generally restricted to non-animate objects. That is to say, using neuter pronouns to refer to animals is not normal, and referring to a person with neuter pronouns is offensive. For example, if we're looking under the bonnet of a car, you might point and say "esto es el carburador" ("este es el carburador" would be equally acceptable). In this circumstance, you might think of "esto es" as "this thing is". However, you would never say "esto es nuestro invitado".
Este and esta are also used as determiners, as in "este chico" or "esta chica". But since there are no neuter nouns, esto can never be used in this way.
Historically, este and esta were accented (i.e. éste and ésta) to indicate their use as pronouns while the unaccented versions were determiners. Since esto can never function as a determiner, it has never been accented in this way. However, the current advice from the RAE is to never accent them, although they consider it acceptable (though optional and not recommended) to accent them where there is the risk of ambiguity.
how esto is used to refer to an idea:
"El carburador está roto. Esto no es bueno."
"The carburetor is broken. This is not good."
If we were referring to the carburetor being "not good," we would use este, but that isn't the case. What's "not good" is the carburetor being broken, which is not a noun, neither masculine or feminine, but an idea. Thus we assign it a gender-neutral word: esto.