It's mainly a British English term that evokes an image of something excessively quaint or charming. Her wardrobe was filled with twee vintage dresses.
Pro Tip 2/3
Subjective Perception
What one person finds twee, another might find appealing. It depends on personal taste. Some may think this dollhouse is twee, while others adore its charm.
Pro Tip 3/3
Mood Impact
Using 'twee' can imply a harmless playfulness or a dismissive sneer, depending on the context. A twee nursery rhyme played in the background, annoying some guests.