I'm unsure what people are building when they say they are building micro services. I don't understand how any company like Uber or monzo end up with 1500 servi

I'm unsure what people are building when they say they are building micro services. I don't understand how any company like Uber or monzo end up with 1500 services to maintain. I mean do they abstract the function of "emailing" out into 50 different micro services. Or 1 micro service?