The title of this blogpost contains two common idioms:
1. During this holiday period many people will be out and about visiting friends and relatives. Out and about means to be away from the home visiting friends, perhaps shopping a bit, and generally having a good time.
2. While they are out and about, they'll probably feast their eyes on the wonderful decorations. Feast their eyes means to enjoy the sight of something.
Learn more idioms with out and eyes with these idiom and expression sheets: