1to sign one's name
2to write brief comments on a document
3visa
4inscribed bamboo stick (variant of 籤|签) (籤|签 · to sign one's name)
Examples
qǐng请nǐ你zài在zhè这gè个dì fang地方qiān签gè个zì字。
请你在这个地方签个字。
Please sign here.
你在这里签个名就行了。
All you have to do is sign your name here.
不要忘记签上你的名字。
Don't forget to sign your name.