Naz, the words este, esta, estos, estas and esto are all different forms of the same word that generally means "this", referring to an object that is close to the speaking person (i.e. "close to me"). The different forms are used for
- este - a singular masculine noun: "este hombre" - "this man"
- esta - a singular feminine noun: "esta mujer" - "this woman"
- estos (!) - multiple masculine nouns: "estos vestidos" - "these dresses"
- estas - multiple feminine nouns: "estas palabras" - "these words"
- esto - a neutral pronoun, not referring to a noun: "Esto es malo." - "This is bad."
The part that creates the most confusion is that estos is the plural form of este, suddenly getting an 'o' there. You would expect the plural form to be "estes", but it doesn't work like that.
The words ese, esa, esos, esas and eso follow the very same pattern. They refer to an object that is close to the person that's listening (i.e. "close to you"). These are generally translated as "that" and "those" in English. Again, esos is the plural masculine form, while eso doesn't refer to any specific noun.
There's also a third group of these demonstratives, used when the object we're talking about is out of reach for both speaker and listener (i.e. "far from you and me"). These are aquel, aquella, aquellos, aquellas and aquello. They also translate as "that" and "those", because English doesn't make a three-fold distinction anymore. A few centuries ago this would be translated as "yonder".
Only nouns get an '-s' when they're pluralised. For verbs it's just the other way around: if you conjugate a verb for the present-tense (singular) he/she/it form, you need to add an '-s' at the end. In all other cases the verb remains in the base form:
- One item costs something.
- Multiple items cost something.
- He loves you.
- They love you.
- The boy reads well.
- The boys read well.
A nice way to think of it is that you only get one 's' per sentence and you can only attach it to the noun or the verb, not both.