When used in the preterite tense, the verb "saber" means to find out.
In a present tense, ther verb saber would mean to know. However, It can change its meaning when conjugated in its preterite form: supe or sabía.
In this case, "supe" in English could be translated as found out into English when refering that you learnt or got specific information about a person or about something.
