After I unpacked, I asked if I could have a guide to show me around the town.

unpacked 是动词 unpack 的过去式。unpack 由前缀 un-（表示"相反动作"）和动词 pack（打包、装箱）组成，字面意思是"拆开打包的东西"，即"打开行李、取出物品"的意思。