The implicit verb is simply “be”:
Some symbols acquire a multitude of meanings,
some [of which] [are] widely shared [meanings],
others [of which] [are] personal [meanings],
[and] some [of which] [are] contradictory, conflicted, or ambivalent [meanings].
This is a common structure to describe different parts of a subject with different adjectives, while avoiding repetition of the subject or verb. For example:
I bought four apples: two red, two green.
All of these are equivalent:
- I bought four apples: two apples [were] red, two apples [were] green.
- I bought four apples: two red ones, two green ones.
- I bought four apples: two red apples and two green apples.
- I bought four apples. Two of them were red and two of them were green.
The last case is one of the relatively rare instances in English where adjectives can be used postpositively, that is, after the noun they modify. This mostly comes up with things like “best possible” (“the best hotel possible”) or in poetic language.