To be spangled is to be decorated with beads, jewels, sequins, or other adornments. The American flag is called star-spangled, because it is full of stars.
Something spangled is covered with little decorations. A shirt with rhinestones all over it is spangled. A hat with little jewels on it is spangled. A banner with beads is spangled. When something is spangled, it’s been spritzed up, spruced up, and made more colorful. Something spangled is usually more interesting to look at: it’s more detailed.