The color green is almost exclusively used in connection with plants in the Bible, and the meaning is closely connected to the meaning of plants as well. Plants, in general, represent facts, knowledge that we can gather from the world. Green plants are ones that are alive and growing. Since life represents love and goodness, it makes sense that green plants are facts that have the potential for good use. It also indicates that they are the kinds of things we learn through directly through our senses, since to identify green plants we need to actually see the greenness.

(Reference: Apocalypse Explained 507; Apocalypse Revealed 426; Arcana Coelestia 7691)

6870. 'And this will be the sign to you that I have sent you' means the recognition that the Divine would go forth from Him. This is clear from the meaning of 'the sign' as the corroboration of truth and consequent recognition that it is indeed so; and from the meaning of 'being sent' as going forth, dealt with in 2397, 4710, 6831, so that 'being sent by God' is going forth from the Divine. It is also the Divine going forth from Him, for one who comes forth from the Divine is receptive of the Divine and extends its influence further.