"My pears are big and good."
Translation:Mé hrušky jsou velké a dobré.
"Mé" is an alternative to "moje." See the link below, and click on Declension if the table is not visible. This may also be covered in the Tips and Notes for the Skill.
Hruška is grammatically feminine, and hrušky is its nominative plural form. The adjective endings are as shown, because they are the correct nominative plural forms for adjectives that modify feminine nouns.
Velký and dobrý would be correct for a singular masculine inanimate noun like, for example, automobil. In the nominative plural, for automobily, the adjective endings would be the same as they are for hrušky. See, for example, the declension table for velký at this handy site: https://en.wiktionary.org/wiki/velk%C3%BD#Declension.