欢笑 means to laugh heartily or joyfully, often describing a group of people laughing together in a happy atmosphere. It differs from 大笑 (a big laugh) by emphasizing the joy and warmth rather than just the loudness. Although the POS is verb, it may occasionally function as a noun in some contexts (e.g. 充满欢笑, full of laughter), but its primary use is to express the action of laughing with delight.