可 (kě) as an adjective means "acceptable," "passable," or "worth doing." It frequently appears as a prefix in compound words like 可以 (can/may) and 可能 (possible). On its own or in classical usage, 可 conveys that something meets a basic standard or is permissible.
这个方案还可以,但不是最好的。
Zhège fāng'àn hái kěyǐ, dàn bùshì zuì hǎo de.
This plan is okay, but it's not the best.
今天的菜味道还可以,就是咸了点。
Jīntiān de cài wèidào hái kěyǐ, jiùshì xián le diǎn.
Today's dishes taste okay, just a bit too salty.
他的表现还算可以,通过了面试。
Tā de biǎoxiàn hái suàn kěyǐ, tōngguòle miànshì.
His performance was passable, and he passed the interview.