if i went on annual for two weeks and one of my colleagues takes over my job temporarily, so she/he is my 'proxy' or 'deputy'? or there's better wording for this?
If he assumes all duties of the position in terms of daily management, then he is designated Acting (Office Manager), Acting (Head of Department).
A person deputizes when they act as your agent, usually for a specific purpose, such as attending a meeting on your behalf, where he will then act as your proxy in casting a vote on your behalf at the meeting. (Usually, the motion/s to be voted on are known in advance, and so the proxy castes his vote as previously instructed to do so by the person for whom he is deputizing.)