It's a bit of a playful expression that is often used to describe someone who enjoys a variety of sweet treats or has a sweet tooth for everything.
Here are some examples of how it could be used:
* "Ella es dulce de todo, le encanta el chocolate, el helado, los pasteles..." (She's sweet of everything, she loves chocolate, ice cream, cakes...)
* "No se puede resistir a nada dulce, es dulce de todo." (He can't resist anything sweet, he's sweet of everything.)
The phrase doesn't have a direct equivalent in English, but you could use phrases like "has a sweet tooth for everything" or "loves all things sweet" to convey the same meaning.