Meaning:
“杀” means “to kill,” and “青” is the color “green.” This term literally means “degreening,” a process to treat fresh tea leaves. The term was also used to depict a method some 2,000 years ago of baking bamboo slips in preparation for them to be written on. Today, however, it is often used to describe wrapping up a film shoot or clinching a project in the general sense.
Example:
A: 你喜欢的女神又有新片杀青。
Nǐ xǐhuān de nǚshén yòu yǒu xīnpiān shāqīng。
Your idol just had a new movie shot.
B: 你是说刘亦菲吗？
Nǐ shì shuō liúyìfēi ma?
Do you mean Crystal Liu?
A: 是啊，不过后期制作可能还要几个月，因为档期排在明年夏天。
Shì a, bùguò hòuqī zhìzuò kěnéng hái yào jǐgè yuè, yīnwèi dàngqī pái zài míngnián xiàtiān。
Sure. But post-production may take a few months, and the film is set to be released next summer.