yo - I nosotros - we
tú - you vosotros - you all (only used in Spain)
él - he ellos - they (at least one masculine element)
ella - she ellas - they (all feminine elements)
usted - formal you ustedes - you plural
The difference between tú and usted is that tú is used with people you are very familiar with and usted for strangers or as a sign of respect. If you would call someone Mr. or Mrs. XYZ, you would use usted.
SER - TO BE
yo soy - I am nosotros somos - we are
tú eres - you are vosotros sois - you are {in Spain}
él es - he is ellos son - they are
ella es - she is ellas son - they are
usted es - you {formal} are ustedes son - you {pl, formal} are
You don't need to use subject pronouns in Spanish
ex. Yo soy de Vermont OR Soy de Vermont = I am from Vermont
Whenever you say a person and "I" - you use the form of the verb for "we"
ex. Pablo y yo somos amigos. = Pablo and I are friends.
When you have anything that is singular that is not "I" and not "you", use the form for he or she.
ex. El Libro es interresante. = The book is interesting.
¿Quién es tu maestro de inglés ? = Who is your English teacher?
When you have anything that is not plural that is not "we" or "you" use the form for they.
ex. Mis amigos son inteligentes. = My friends are intelligent.
Las hamburguesas son deliciosas. = The hamburgers are delicious.