QUICK ANSWER
"Es" is a form of "ser", a copular verb which is often translated as "to be". "Con quien" is a form of "con quien", a phrase which is often translated as "who ... with". Learn more about the difference between "es" and "con quien" below.
ser(
sehr
)A copular verb links the subject of a clause to the predicate (e.g., My brother is tall).
An intransitive verb is one that does not require a direct object (e.g., The man sneezed.).
a. to be made of
El casillero antiguo de mi abuela es de roble.My grandma's antique dresser is made of oak.
a. to root for
Yo soy del mejor equipo del mundo: FC Barcelona.I root for the best team in the world: FC Barcelona.
An impersonal verb is a verb with no apparent subject (e.g., Llueve en España.).
a. to be
Son las siete de la mañana.It is seven in the morning.
Era de noche cuando llegaron.It was night when they arrived.
An auxiliary verb, or helper verb, is a conjugated verb that comes before a main verb and determines the main verb's tense, mood, or aspect (e.g., I have gone.).
a. to be
El edificio fue diseñado por un equipo de arquitectos.The building was built by a team of architects.
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
con quien(
kohn
kyehn
)A phrase is a group of words commonly used together (e.g., once upon a time).
a. who ... with
Soy enfermera y el médico con quien trabajo es cardiólogo.I'm a nurse and the doctor who I work with is a cardiologist.
Maribel, con quien fui a Mallorca, es mi prima.Maribel, who I went to Mallorca with, is my cousin.
b. with whom (formal)
A word or phrase used to refer to the second person formal “usted” by their conjugation or implied context (e.g., usted).
En cuanto la conoció, supo que era la mujer con quien quería pasar el resto de su vida.The moment he met her, he knew she was the woman with whom he wanted to spend the rest of his life.
c. no direct translation
This refers to an idiomatic word or phrase for which there is no word-for-word translation.
Esa amiga con quien estoy en la foto es de Madrid, como tú.That friend I'm with in the photo is from Madrid, just like you.
El chico con quien me viste en la fiesta es mi hermano, no mi novio.The boy you saw me at the party with is my brother, not my boyfriend.