What are all the symbols on the Encinas Family Crest?

Many items on that family crest are no more than decoration. The helmet with the oistrich feathers is a very common addition to numerous family crests, simply indicating that a family has a martial background (or would like to give us that impression). The yellow-and-green curly decoration left and right of the crest is called the 'mantle'. It has no meaning other than decorative and in most cases was made up by the person designing the crest just to fit in nicely with the color scheme of the crest itself.
The tree in the crest itself is an olm oak tree that has the Spanish (Galician) name Encina. So it's merely an indication of the family name. The two greyhounds are - just as the helmet above - an indication that the Encinas family belonged to the wealthy landowner class that could afford to keep greyhounds for sport and entertainment.