This is a self-portrait of a recognized fictional character, an Avatar, in a forest. With the presence of weird looking plants, the surrounding background reflects that of a foreign world as well. The colours of the picture focus on a greenish/bluish hue.
Based on the background, we can gather that the forest is his home and he is a native there. The colours of the background and character are quite similar thus, signifying their close relationship with each other. From the picture, we can also decipher that the character, a hunter (judging from his dressing), is very reliant on the forest.
In terms of trying to reflect the life of the character, it is relatively successful as the character seems to blend in with the surroundings. If the aim of the picture is to promote the movie, it is a successful advertisement. It is able to convey to the target audience the setting of the movie. However, the Avatar was not given a personality, judging from his static facial expression.