Marble
noun
When you see a katakana word, it's a safe bet that it is a foreign loan word from somewhere else. This one's interesting, because it combines katakana and kanji! The first marble came to Japan from Portugal, so the ビー part of the word is short for "vidro," which means "glass" in Portuguese. Anyway, don't get thrown off by that ビー. Maybe just imagine that your favorite marble is black and yellow like a bee.
びーだま, ビーだま
If you know katakana as well as the reading that you learned when you learned the kanji 玉, you should be able to read this. Just watch out for the rendaku.
ビー玉は小さい丸い玉です。
Marbles are small, round balls.
二月三日に大きなビー玉のレースがあります。
There is a big marble race on February 3rd.
ママの目玉、ビー玉みたいできれいだね。
Mom, your eyeball is beautiful like a marble.