1 block only allow about 2000 transactions. Does it mean every 10 minutes, bitcoin can allow 2000 transactions? Hi I very new to bitcoin and don't understand this. Isn't this 2000 too small? I thought there would be more than 10,000 transactions going around every 10 minutes. Especially when there is an ICO going on.
2-3000 transactions can be included in each block. But that does not mean that only that many transactions can be made every 10 minutes. There can be, and has been, several thousands more transactions made than can fit into the next block. That just means that several thousand transactions won't be confirmed in the next block and will have to wait for blocks that come later.

There are many proposals that are in their activation stages that will increase the Bitcoin's capacity so that much more transactions can be included in each block. However these are all not yet deployed; they either require miner signalling or community consensus (everyone, including miners) to activate, and none of those have happened for any of the proposals yet.


  Especially when there is a ICO going on


ICOs don't use Bitcoin.