What does "life's a beach" mean?

Solution 1:

It's a riff on the phrase "life's a bitch" (meaning life can be difficult and unpleasant) which turns it around into a positive. "Life's a beach" means that, at that moment at least, life was nothing but wonderful for David Beckham and Sofia Vergara. Think about beaches: sun, sand, water, beautiful people in bathing suits ... you get the idea.

Solution 2:

It means something positive. Almost like "Life is Good". Who doesn't like a Beach? The beach makes you relaxed, feel warm, have fun in the water, enjoy life. "Life's a Beach" denotes that life is good or great. The phrase was invented to counteract the negative phrase of "Life's a bitch".