ICO is the acronym for Initial Coin Offering. Well, if you don’t what it is, I really wonder what you are doing here 😀
ICOs are meant to crowdfund cryptocurrency related project. In exchange of money of any sort (most likely cryptos, but it is not derogatory), they provide you with a coin or token that is tradable on cryptocurrency markets, hence the “Coin” part. The “Initial” part means that this process is supposed to be the first distribution of the said coins. It is often the last too, but not always.