Green is the color of big beasts. They join the game early, and are usually stronger than the corresponding creatures that other colors can field. Their power then scales up, but the scale is pretty linear and doesn’t pack many surprises.
In addition to solid creatures, green has ways to make them stronger (sometimes permanently).
Green cards sometimes pull a creature straight out of the deck. That way, even if you only have one copy of some special creature, you can still bring it onto the battlefield reliably. Green is great at drawing extra lands and can also be good at drawing extra cards — although you need to be dominating combat to do so. When you get to search your cards, you have to show everyone what you find, because there are always limitations on what card types you can get.
In almost every game, some creatures are going to die. Green is pretty good at noticing cards in the graveyard and using them again. The metaphor exhibited is something like cultivation of crops with mulch from decomposed cohorts.
Enchantments are cards that modify the rules of the game. Green has access to a lot of useful enchantments — and it is also the color that is best at getting rid of ones it doesn’t like (which it can also do to artifacts).
Another really important strength of green decks is their variety of fast ways to produce mana — the energetic currency that you spend to cast spells. Green nearly monopolizes the creatures and spells that ramp (increase) and fix (diversify) your mana base.
Green may be the easiest color to play. It presents a straightforward strategy that unfolds quickly. Many of your choices are uncomplicated (naturally).