Subject pronouns are the placeholders we use for proper nouns to save time and space. I is a subject pronoun. So is you, we, they, etc.
|Ustedes||You (formal, plural)|
|Nosotros||We (male, or mixed gender)|
|Nosotras||We (all female)|
|Ellos||They (male, or mixed gender)|
|Ellas||They (all female)|
|Vosotros (Spain only)||You (plural and informal)|
Subject pronouns are used very similarly in Spanish as they are in English. There are some differences, however. For example, you’ll notice that there are two pronouns for “we” and “they”: one for masculine groups, and one for feminine groups. Whenever there is a group comprised of both males and females, we use the masculine plural (for example, if you want to talk about a group of three women and one man, you would use ellos.) There are also two different pronouns for ”you”: tú, and usted(es). Tú is an informal pronoun, used with friends or close acquaintances and family. Usted, on the other hand, is more formal and respectful–it’s used for people you don’t know very well, or for elders. Ustedes is used for “you-all,” either formally or informally. Vosotros is a pronoun used only in Spain, to talk about either “you” in the plural or to say “you” formally.