On average there are 63,000 searches per second on Google.
That translates to 3.8 million searches every single minute and 228 million searches per hour which is a lot of searches as there are a lot of people using Google daily and every second and every minute.
Those amount of Google Searches means that in a year around 2 trillion searches done every year on Google.
Google is as of now the most popular search engine and most people in the world do use Google Search but some people still use Bing Search or Yahoo Search for their searches.
So there are a lot of internet users doing searches on the internet every single second and now with tablets, phones etc searches are done on those devices while commuting, traveling etc.
So more people have a computer in their pocket or in their hand now that they can easily search things so Google, Bing and other search engines get a lot of searches per day.