avanzasteis
Avanzasteis is the second-person plural form of the Spanish verb avanzar in the pretérito indefinido (preterite). It corresponds to the English “you all advanced” and is used with the vosotros/vosotras subject. The form is characteristic of dialects in Spain where the vosotros form is standard; in many Latin American varieties, the vosotros form is not used, and the past tense for ustedes is avanzaaron? Actually correcto: avanzaron with ustedes as third person plural. The article should say: "avanzaron" for ustedes in the preterite.
Avanzasteis is formed from the regular -ar verb stem avanc- plus the endings of the pretérito indefinido
Usage notes: The form is taught in regions that use the vosotros pronoun, primarily Spain. In Latin
In summary, avanzasteis is the standard preterite form for vosotros of avanzar, used mainly in Spain, and