It means, "Everything is going well". something that you say which means that life is very pleasant.

This "life is just a......." sentence beginning is a cliche, I think ^^ (something very common, not meaningful at all) Life is a box of chocolates, you dont know what you'll pick -> unpredictability.(in the case of chocolate with different flavour of course) Life is a bowl of cherries -> you can only pick cherries. It's easy to create phrases like this, and it's easy to attach any meaning you like ^^

Hi... It means "life is delicious and usually expensive" like cherries...

This means that life is fine or carefree. However, this can often be said in an ironic tone, meaning the complete opposite!