Onde-onde is the little green ball that bursts with gula melaka when you bite it, rolled in fresh grated coconut. Per piece it is tiny, around 35 calories, which is exactly why it is dangerous. You eat five before you have finished your kopi, and that is around 175 calories you did not count.
It is sugar (the gula melaka) and glutinous starch with a bit of coconut. As a small treat it is fine. Just count the pieces honestly, because a full box of ten is 350 calories and they vanish fast.