Flowers represent the fragility of life and plucked flowers indicate the early severance of a life in bloom. A lion is indicative of courage and an arrow represents mortality. A snake with its tail in its mouth indicates everlasting life in heaven, while a coiled snake indicates sin. Roosters are common in some cemeteries, representing resurrection. The pelican represents redemption through Christ, while ants indicate Christian industriousness.
Scales are indicative of the weighing of justice for the judgment of the dead.
Sometimes there will be Latin phrases carved on stones. There are many other such phrases that can be interpreted with a simple Latin dictionary. They were sometimes selected in advance of death by the person whose grave the stone was to adorn. Usually, however, they were chosen by the surviving family. There are some excellent websites you may use for your reference.