单位 (dānwèi) means "unit" and can refer to a work unit (employer or organization), a unit of measurement, or a standard unit. In modern Chinese, 用人单位 means "employing organization" or "employer." The specific meaning depends on context.
你在哪个单位工作?
Nǐ zài nǎge dānwèi gōngzuò?
Which work unit do you work at?
他刚换了一个新单位,离家比较近。
Tā gāng huàn le yī ge xīn dānwèi, lí jiā bǐjiào jìn.
He just switched to a new work unit, which is closer to home.
我们单位每年组织一次体检。
Wǒmen dānwèi měi nián zǔzhī yī cì tǐjiǎn.
Our work unit organizes a physical examination once a year.