QUICK ANSWER
"This" is a pronoun which is often translated as "este", and "she is my sister" is a phrase which is often translated as "es mi hermana". Learn more about the difference between "this" and "she is my sister" below.
this(
thihs
)A pronoun is a word that stands in for a noun (e.g., she).
d. así
Is this enough for you or would you like a bigger piece?¿Así te llega o quieres un trozo más grande?
An adjective is a word that describes a noun (e.g., the big dog).
a. este (masculine)
This winter has been the coldest one in twenty years.Este invierno ha sido el más frío en veinte años.
she is my sister(
shi
ihz
may
sihs
-
tuhr
)A phrase is a group of words commonly used together (e.g., once upon a time).
1. (general)
a. es mi hermana
Let me introduce you to Melanie. She is my sister.Te presento a Melanie. Es mi hermana.