The phrase "hook attachment" refers to something that is connected or joined by a hook. It could be a small item or tool that has a hook-like structure allowing it to be attached to another object securely. Full definition
Add flour and salt and mix with dough hook attachment until combined. (citrusanddelicious.com)
With the dough hook attachment on, start mixing on low speed adding in the melted butter, pumpkin puree, 1/4 cup sugar, pumpkin pie spices and salt. (atreatsaffair.com)
Combine using a whisk, wooden spoon or dough hook attachment in a stand mixer. (gateaugato.com)