行动 (xíng dòng) means action, movement, or to take action. 行 relates to movement or conduct and 动 means to move. Together they form a noun describing purposeful action or the act of moving and doing. The phrase 采取行动 (cǎi qǔ xíng dòng, to take action) is a standard formal expression. 行动 can also refer to physical mobility (行动不便, to have limited mobility).