Hi Camyla! Here's my thoughts:
“他把他的自行车刷成红色”
这个句子在汉语中叫做“把字句”,是一种句式。“把”没有实际意义,只是表示“他”和“他的自行车”之间的主动关系——“他”对“他的自行车”做了什么,而不是“他的自行车”对“他”做了什么。
“他”是主动者,“他的自行车”是被动者,“刷成红色”表示动作。
“刷成”的“刷”就是paint,“成”的意思是“成为、变成”。他把他的自行车用油漆“刷”了,现在他的自行车“变成”了红色。也就是丽王老师说的paint into。
(It is a sentence structure called "把字句" in Chinese. "把" doesn't have a practical meaning. It only signifies the active relationship between "he" and " his bike" --- he did something to his bike instead of his bike did something to him.
In your sentence, "he" is the active one and "his bike" is the passive one, and "painted into red" is his action.
“刷” means "paint", and “成” means "into". He "painted" his bike with red paint, so now his bike is turned "into" red. I'm inspired by Teacher丽王. :)
Hope it helps! :)