Something that's bubbly is frothy or fizzy, full of bubbles. You might prefer to bathe in a hot, bubbly bath every night.
Seltzer and ginger ale are both bubbly, fizzing with tiny bubbles, and your blueberry crisp recipe might say "Bake until hot and bubbly." When you describe a person as bubbly, you're referring to a talkative, cheerful personality. The first person you meet at a new school might be the bubbly girl who sits next to you in math. If someone offers you "a glass of bubbly" at a party, they're using a common nickname for champagne.