It's a phrase used to ask about someone's past personality or appearance. It's similar to asking "What were you like as a child?" or "How did you used to be?"
Here are some examples of how it could be used in a conversation:
* "Como eras en la escuela?" (What were you like in school?)
* "Como eras antes de conocer a tu pareja?" (What were you like before you met your partner?)
* "Como eras cuando tenías veinte años?" (What were you like when you were twenty years old?)
It's important to note that the tense of the verb "ser" (to be) is in the imperfect tense ("eras"). This indicates that the speaker is asking about a past state or condition that has since changed.