The image is a blackboard, on which a Japanese onomatopoeia called "????" in hiragana or "kirakira" is depicted. This onomatopoeia is used in the situation when the stars or jewels are shining brilliantly. There is a good website for learning Japanese language, particularly Japanese onomatopoeia. For it, see my below comment.
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Japanese onomatopoeia-kirakira free icon was designed by yamachem for icons Png and presented to its users.
yamachem
2/5/2018